Condensed Matter

Exchange alone gives the electron gas a local field factor with a sharp peak just below 2kF. Quantum Monte Carlo finds none. Both spin channels are computed here from their lowest diagrams with a dynamically screened interaction and no fitting. Parallel spin correlation is the negative image of exchange and removes about half the peak; the calculated spin-resolved factors account for the QMC data at rs = 1 and 2, and at q = 0 for the compressibility and spin susceptibility obtained from the ground-state energy. The two classes of diagrams are the two terms of the kernel of Hedin's vertex equation, of which the second is routinely dropped.

We study a frustrated seam produced by literal reflection gluing of Wen's plaquette model on a closed lattice Klein bottle. The seam operators anticommute along two cycles for even circumference and one cycle of twice the length for odd circumference. Their algebra reduces to free Majorana rings, while the commuting bulk stabilizers constrain the allowed ring sectors. This bulk locking yields exact ground energies, excitation gaps and degeneracies, checked by phase-aware Pauli traces and finite-size diagonalization, including two 24-qubit energy predictions. The seam degeneracy is not topological: the single-site seam fields tested split it at second order. We contrast this obstructed gluing with consistent toric-code realizations. An edge register preserves the anyon labels; a Hadamard-dressed site register has colour-dependent seam transport, with ground-state degeneracy 2 or 4 for even circumference and a sign-frustrated exception at odd circumference. For the enumerated lattice isometries and sizes, we compute logical gates and distances, distinguishing abstract qubit relabelling from local hardware depth. Finally, on three 16- and 24-qubit lattices, chiral matter selects a holonomy doublet whose electric-field splitting follows two competing tunnelling routes. These matter results remain finite-size statements. The main result is the exact obstructed-seam solution with bulk sector locking; the register, gate and matter calculations delimit its relation to topological codes.

Can artificial intelligence (AI) move beyond solving well-defined problems to contribute to open-ended discovery in fundamental physics? Could AI propose what to explore, identify unexpected phenomena, and uncover their mechanisms? We address this using MOSAIC (Multi-agent Open-ended Scientific Analysis and Investigation through Collaboration), a collaborative swarm of AI agents (Claude Opus 5.5), to tackle a longstanding bottleneck: the small energy gaps limiting the robustness of fractional topological order and the study of anyons at higher temperatures. Rather than prescribing a model, we ask frontier models (GPT-6 Astra) to propose a theoretical framework, which MOSAIC explores through diverse strategies and rapid exchange of ideas. This reveals a striking finding: although ideal quantum geometry is considered favorable for fractional states, departing from this limit can dramatically enhance their robustness, with many-body gaps more than an order of magnitude larger than in the ideal case. Without centralized coordination, the agents explored autonomously, combined findings across agents, and formed insights from individual runs, outperforming isolated agents with the same tools. AI-assisted theoretical analysis further develops simplified models with an analytical gap enhancement factor that is unbounded within the single-band approximation. Remarkably, AI identifies the real-space quantum metric, rather than the momentum-space one, as the key quantity governing the many-body gap, revealing how flat-band wavefunctions shape two-electron interactions and yielding an index computable from single-particle wavefunctions without many-body ED to guide gap optimization. Our study demonstrates how collaborative AI agents can integrate exploration, discovery of unexpected physics, and theoretical understanding, opening new possibilities for AI-driven research in fundamental physics.

Strange metals pair a resistivity linear in temperature with a specific heat $C/T$ rising logarithmically on cooling. We find that, if electrons scatter off a local critical bath, the coupling cancels in the ratio $Q$ of their coefficients, leaving two measurable numbers: how slowly the bath relaxes, seen in photoemission or optics, and the share of critical entropy that relaxes current. Baths form classes: $Q\le4.91$ for a conformal bath, as SYK models confirm; 9--15 for the Yukawa--SYK field; and far less for Kondo lattices. LSCO, at $Q\approx9$, exceeds the conformal bound, pointing to the Yukawa--SYK field.

Designing sustainable alloys must reconcile high performance with real-world constraints, including feedstock scarcity and variability, processing and energy requirements, regulatory thresholds, and economic limitations. Addressing these constraints reaches far beyond today's conventional performance-focused frameworks. It needs to consider not only complex property-processing-performance trade-offs but also sustainable production pathways. Here, we propose a physics-informed ensemble (PIE) learning framework that integrates fundamental structure-property relationships with processing routes and sustainability criteria for mechanism-based alloy design. It predicts properties from composition-microstructure relationships and infers processing routes under sustainability constraints, establishing an interdisciplinary approach to identifying sustainable alloy solutions. We validate the approach for Mg alloys, a lightweight yet energy-intensive metallic material class, considering performance, cost, and carbon emissions. Trained on a benchmark dataset, the PIE model systematically explores plausible alloy compositions and microstructures to construct a digital library of millions of candidate alloys. From this space, we identify two sustainable Mg alloy solutions that overcome the conventional performance-cost-emission trade-off: a rare-earth-containing alloy increases yield and tensile strength by 72.8 percent and 61.1 percent, respectively, over alloys from the same family at comparable cost and emissions; and a rare-earth-free alloy reduces cost and carbon emissions by 40.4 percent and 88.9 percent, respectively, relative to its primary-feedstock counterpart, without compromising mechanical performance. This work introduces a general, physics-informed, and quantifiable framework for designing sustainable alloys under real-world constraints.

We ask how much of a large random system must be observed before a global average can be inferred with controlled uncertainty. For the random transposition shuffle, a conjugate Bayesian estimator of the average displacement, computed from $m$ uniformly sampled cards, has relative uncertainty $1/\sqrt{2m}$, independent of the deck size $n$. The law of total variance exposes a second error, the floor $R_n$, which arises because the observed configuration is a single draw from equilibrium: no relative tolerance below $\kappa\sqrt{R_n}$ can be certified, even by a census. For the shuffle we derive $R_n=(2n^2+7)/\bigl(5(n-1)^2(n+1)\bigr)$ and show that the posterior remains calibrated. At the critical point of the two-dimensional Ising model the floor of the energy vanishes, whereas that of the magnetisation stays near $0.072$; its mean-field limit is $\sqrt{2}-1$. For correlated fields read by sensor networks, the usual 95\% interval covers the ensemble mean in 7\% of cases. Bounding the floor from one realisation, as in single-chain Monte Carlo diagnostics, requires an assumption on the decay of correlations.

Non-invasive thermometry is highly desirable in cryogenic experiments to avoid the self-heating inherent in conventional sensors. In previous work, temperature was probed via the vibrational eigenfrequency of a suspended single-layer SiNx nanofilm. However, the turning point of the frequency-temperature curve limited the usable measurement range. Moreover, the slow thermal response confined measurements to a stepwise protocol with only discrete temperature points. Here, we show that these limitations can be overcome with a suspended bilayer SiNx/Al nanofilm, whose temperature-dependent vibrational eigenfrequency provides a monotonic, continuous, and repeatable temperature readout. The frequency-temperature dependence is governed by the mismatch between the effective coefficients of thermal expansion (CTE) of the bilayer and the substrate, which makes the turning point tunable through the thickness ratio of the two layers. Over the 90 K to 300 K range, we characterize three bilayer nanofilms with different Al layer thicknesses and show how the turning point shifts with the thickness of the Al layer. For the sample with 72 nm Al, the turning point is pushed beyond 300 K, yielding a monotonic negative temperature coefficient over the entire 90 K to 300 K range. Combining a thin Al layer on the SiNx film with improved thermal anchoring of the chip shortens the thermal response to below 1 s, enabling continuous frequency tracking at a ramp rate of 3 K/min. We also demonstrate that the nanofilm with a 72 nm Al layer achieves a repeatability better than 150 mK above 175 K, and the frequency resolution of 1 Hz corresponds to a temperature resolution of ~5 mK.

Cutting and shuffling (CS) rearranges fluid without stretching, but homogenisation requires diffusion (D); this interaction is not well understood. We show that CSD is a coarsening process, with scale $\bar\ell=L(n_c\mathrm{Pe}/2)^{-1/3}$ rather than the Batchelor scale, and that cutting acts as a fractional Laplacian in wavenumber, giving the exact mixing rate $\gamma=2^{1/3}|a_1'|n_c^{2/3}\lambda\mathrm{Pe}^{-1/3}$ for $n_c$ cuts per event at rate $\lambda$, with $a_1'=-1.0188\dots$ the first zero of $\mathrm{Ai}'$. This holds in any dimension for random and deterministic protocols, extends to finite-time mixing, and places CSD in a known non-equilibrium universality class.

Near-surface bismuth donors are promising for silicon quantum devices because of their rich electron-nuclear spin structure and long spin coherence, but their electrical activation is strongly influenced by implantation-induced amorphization. We compare redistribution and electrical activation of 20 keV Bi implanted directly into Si and after Si preamorphization. The two routes produce amorphous-layer depths of approximately 47 nm and 177 +/- 15 nm, respectively. After annealing at 650 C for 300 s, Rutherford backscattering spectrometry and channeling reveal comparable substitutional Bi fractions of 91 +/- 2% and 89 +/- 4%, whereas Hall measurements indicate Hall-derived electrical activation yields of approximately 60% and 90%, respectively. Depth-resolved ion-scattering analysis reveals a buried Bi-related feature at or beyond the initial amorphous/crystalline interface, within the end-of-range region, together with increasing surface segregation at higher annealing temperatures. The buried feature is consistent with trapping near residual end-of-range defects. X-ray photoelectron spectroscopy and low-temperature photoluminescence on the Bi-only sample reveal no resolvable Bi-oxide contribution and a donor-related optical signature, respectively. These results show that amorphization depth and regrowth geometry govern Bi redistribution and influence electrical activation beyond substitutional incorporation alone.

We present AlgebrasTQD, an open-source code written in GAP (Groups, Algorithms, and Programming), for computing condensable algebras and the corresponding topological boundaries and interfaces of twisted quantum doubles $D^\omega(G)$. These algebras can be used to classify 1+1d gapped and gapless phases whose symmetry is related by gauging to a finite group $G$ with anomaly $\omega\in H^3(G,U(1))$, to study 2+1d anyon proliferation and to construct logical gates in non-Abelian topological quantum codes. The functions in AlgebrasTQD compute all condensable algebras $A(H,F,\gamma,\epsilon)$ with their algebra structure and anyons, sort them into isomorphism classes and identify the twin algebras that are inequivalent but share the same anyon decomposition. AlgebrasTQD also determines all the subalgebra relations, the corresponding Hasse diagram and the types of 1+1d phases for any chosen, possibly non-invertible, group-theoretical symmetry. For non-maximal algebras, the code computes the reduced topological order with its $3$-cocycle and the map of anyons across the topological interface. Finally, AlgebrasTQD includes functions that construct certain non-Clifford logical gates via non-Abelian surface codes. We summarize the formulas that are implemented in the AlgebrasTQD code, and we illustrate its use with Abelian and non-Abelian groups including $\mathbb{Z}_2^3$ with $\omega_\text{III}$, $D_8$, $A_4$ with and without anomaly, twin algebras and twin phases, and the Clifford-hierarchy gates in quantum doubles of dihedral groups. All arithmetic is exact and AlgebrasTQD can be used with any finite group $G$ and 3-cocycle $\omega$, limited only by the time and size of the calculation. The code is available at this https URL

We show that the steady state of a periodically driven Bose gas coupled to a thermal bath features emergent Fermi surfaces both in its high temperature and Bose-Einstein-condensate (BEC) states. These emergent Fermi surfaces are non-analyticities in the occupation function as a function of momentum arising from the lack of detailed balance of collisions away from equilibrium. They are stronger in the BEC than in the normal gas, and can be more robust against finite temperature smearing than the usual equilibrium Fermi surfaces of Fermi gases. We also show that they give rise to analogous rich phenomena, such as Friedel oscillations in the density correlations and quantum oscillations in response to applied magnetic fields controlled by their areas, albeit with marked quantitative differences. Our results establish non-equilibrium conditions as a promising alternative pathway to achieve the long-sought-after emergence of Fermi surfaces in bosonic system. We outline strategies to experimentally discover these exotic states in ultra-cold atomic clouds.

Bayesian inference with a mismatched model can develop an overconfident phase, characterized by posterior agreement without faithful reconstruction of the true state. We study Bayesian inference from noisy bond measurements of an Ising model in its paramagnetic phase, with true inverse temperature $\beta$ and measurement-noise strength $\Delta$, while inference assumes corresponding parameters $\beta_Q$ and $\Delta_Q$. Using replica field theory, we analytically show that the overconfidence phase can occur when inference underestimates the measurement noise ($\Delta_Q < \Delta$) or assumes a lower prior temperature than the true one ($\beta_Q > \beta$). An exact change of variables maps the problem to a correlated random-bond Ising model, where the informative, uninformative, and overconfident phases correspond to ferromagnetic, paramagnetic, and spin-glass phases, respectively. We further perform Monte Carlo simulations of the mapped model in three dimensions and establish a finite overconfident region between the informative and uninformative phases, consistent with our analytical prediction. Finally, we show that the true model parameters can be inferred directly from the measurement records, providing a natural route to calibrating the inference model.

We use macroscopic fluctuation theory (MFT) to establish the typicality of charge-transfer statistics and entanglement dynamics in the quantum symmetric exclusion process, a model of stochastically hopping free fermions with diffusive transport and long-range quantum coherence. We show that the leading long-time charge-transfer full counting statistics of individual noise realizations coincide almost surely with those of the classical symmetric exclusion process (SSEP), in equilibrium and following quenches from arbitrary occupation-diagonal product states. Our results apply to transient fluctuations in the thermodynamic limit, extending previous work that has primarily focused on stationary regimes. Our approach compares the noise averages of the charge-transfer generating function and its inverse. The former reduces to SSEP, while the latter maps to an auxiliary Brownian energy process whose MFT saddle-point problem is related to that of SSEP, yielding matching large-deviation exponents. Through free-fermion identities relating entanglement to subsystem-number fluctuations, this establishes the self-averaging of the covariance-matrix eigenvalue distribution and of Rényi and von Neumann entropies. We obtain asymptotically exact predictions for entanglement growth from domain-wall and Néel initial states, in excellent agreement with numerical simulations.

We establish an experimentally accessible route to identifying Majorana surface states through their intrinsic Ising spin response, using UTe$_2$ as a concrete platform. The key is to extend the Majorana correlations into an adjacent metallic film via the superconducting proximity effect, thereby making the otherwise surface-localized response accessible to NMR measurements. Remarkably, disorder further sharpens the Majorana signature: impurity scattering suppresses the conventional $p$-wave proximity correlations while preserving the Majorana contribution, yielding a giant Ising-anisotropic enhancement of the NMR relaxation rate. This approach also offers a powerful means to distinguish among candidate pairing symmetries.

We investigate the interplay between confinement and Krylov complexity in the long-range transverse-field Ising chain, where power-law interactions $\sim 1/r^{\alpha}$ generate an effective confining potential between domain walls without an explicit symmetry-breaking field. Using the time-averaged Krylov state complexity after a quench as a diagnostic, we find that the complexity is strongly suppressed and only weakly system size-dependent at small $\alpha$ and small transverse field $h_x$, where confinement is strongest, and crosses over to rapid growth at larger $\alpha$, where it increases with system size. Within the confined regime, the oscillation frequencies of the complexity agree with the meson masses of an effective two-kink model, with the dominant frequency growing linearly with the lightest meson mass and the time-averaged complexity decreasing approximately as its inverse square. We further study operator Krylov complexity at finite temperature using the Wightman inner product. At low temperature, it exhibits bounded oscillations that directly encode the meson spectrum, whereas this structure is progressively washed out as the temperature increases. These results identify Krylov complexity as a spectroscopic probe of interaction-induced confinement and reproduce, in a microscopic lattice model, the hallmarks of Krylov complexity identified in confining field theories.

Conditional mutual information (CMI) characterizes dependence between two regions conditioned on an intervening buffer. Its characteristic decay length, the Markov length, has recently been identified as a diverging length scale at mixed-state phase transitions. Here, we investigate CMI dynamics in one-dimensional classical stochastic models and propose a universal scaling form for systems whose Markov length diverges with time. We derive this form in the inactive phase of parity-conserving directed percolation, where domain-wall coarsening generates a growing length scale and a self-similar probability distribution. We introduce a Hankel-based truncation scheme that enables matrix-product-state simulations at long times and over large spatial regions. Using this method, we verify the proposed scaling both in the inactive phase and at the nonequilibrium critical point, where the dynamical critical exponent governs Markov-length growth. More broadly, the same scaling form captures cases in which collective inference sets the diverging Markov length. Despite these distinct mechanisms, the CMI between fixed microscopic regions exhibits a common scaling dimension of two. Finally, we extend this framework to temporal CMI, establishing an analogous relation between the strength of conditional dependence in time domain and its characteristic memory time.

The dramatic slowing down of liquids approaching the glass transition remains unresolved, partly because competing theoretical explanations are difficult to discriminate. Indeed, several mature, contrasting frameworks account for the main features of glassy phenomenology, making agreement with familiar observations a weak basis for identifying the microscopic mechanism responsible for the slowdown. Recent numerical advances are changing this situation in two complementary ways. Deep equilibration extends controlled equilibrium studies into regimes previously accessible only by extrapolation, allowing established predictions to be stress-tested over a broader dynamical range. At the same time, new numerical methods increasingly provide direct access to theory-specific quantities such as configurational entropy, static lengths, elastic properties, and local activation barriers. I discuss how these developments constrain thermodynamic, facilitation-based, elastic, and excitation-based descriptions. The emerging picture is not yet a unique theory, but a set of increasingly discriminating tests that can reveal where apparently successful laws cease to be universal and identify the microscopic ingredients that causally control the activation barrier.

Scanning transmission electron microscopy (STEM) is a versatile, multi-modal method for studying materials at the nanoscale. It integrates multiple signal sources to provide atomic resolution imaging alongside spectroscopy for elemental composition and electronic structure. Despite its utility, few datasets spanning multiple years of data have been published. We introduce STEM-Bank-26, a 929 GB open dataset of 37,921 STEM images that spans 1,095 material samples across 1,499 sessions and includes energy-dispersive spectroscopy (EDS) or electron-energy loss spectroscopy (EELS) data for 65.5% of sessions. We extract microscope control trajectories by comparing metadata between sequential images and provide tools for building similar datasets from archival data. To our knowledge, this is the largest openly available dataset that integrates experimental STEM, EDS and EELS data across a broad distribution of samples and sessions.

Simulating the coupled magnetic and rotational dynamics of suspended magnetic nanoparticles (MNPs) over experimentally relevant timescales remains computationally demanding, particularly under low-frequency alternating magnetic fields. Here, we develop a hybrid Brownian Dynamics--kinetic Monte Carlo (BD--kMC) framework that combines thermally activated magnetic switching with particle rotation while retaining local fluctuations of the magnetic moment. These fluctuations are incorporated through Metropolis Monte Carlo (MC) sampling, allowing the moment to depart from the energy minima and thereby capturing the thermally averaged anisotropy torque that governs particle rotation. To preserve the distinction between local fluctuations and magnetic reversals, a barrier-trapping criterion confines MC trial moves to the current energy well, leaving thermally activated switching to the kMC process. For non-interacting single-domain MNPs, comparison with stochastic Landau--Lifshitz--Gilbert (LLG) simulations demonstrates agreement in the equilibrium torque and stationary easy-axis orientation, including the field-driven transition from predominantly perpendicular to parallel alignment. The resulting BD--kMC framework provides an efficient approach to coupled magnetic and Brownian Dynamics, reducing the computational cost of exploring the long timescales relevant to low-frequency magnetic applications.

We introduce a simple correlation function for quantifying hidden local anisotropy in disordered materials. Developed in analogy with the three-dimensional difference pair distribution function (3D-$\Delta$PDF), our approach identifies structural correlations that are lost through averaging over bulk symmetry. The same approach might be applied to models of disordered crystals, amorphous materials, and liquids alike.

Electronic correlations reorganize not only the energies of individual electronic states but also the collective structure of the spectrum. Here, first-principles density functional theory calculations combined with random-matrix spectral statistics are used to examine this reorganization in gamma-Ce within a static spin-polarized DFT+U+SOC description. We distinguish the effects of the Coulomb interaction U from those of the exchange interaction J by analyzing nearest-neighbor spacings, reduced spacing ratios, band velocities, and band curvatures across the Ce-4f manifold. Increasing U does not produce a monotonic transition between Poisson- and Wigner-Dyson-like statistics; instead, the region of strongest level repulsion migrates across the 4f manifold as the interaction increases. Exchange produces a qualitatively different response. At fixed U, strongly repulsive and strongly clustered spectral regions coexist within the same 4f manifold even while the total spin moment and 4f occupation remain nearly unchanged. The clustering persists after resolving the spectrum into its dominant j = 5/2 and j = 7/2 components and differs strongly between calculations having the same numerical value of U-J. Within the present DFT+U+SOC description, the spectral response therefore depends on the separate Coulomb and exchange interactions and cannot be represented completely by a single effective U-J parameter. These results show that energy- and character-resolved spectral statistics expose correlation-driven electronic reorganization that is hidden by conventional integrated observables.

The choice of statistical ensemble has a measurable impact on the statistical description of Bose-Einstein condensates beyond the well-known grand canonical anomaly. We develop a segmented-contour approach for the ideal Bose gas, which refines the saddle-point approximation by including non-Gaussian corrections in the canonical and microcanonical ensembles. The method applies to a broad class of noninteracting spectra, and provides efficient access to condensate fluctuations, higher moments, and correlation functions. For a three-dimensional harmonic trap with fixed anisotropy, we find that the ratio of the maxima of the microcanonical and canonical condensate-number variances approaches the theoretically predicted asymptotic value $1-3\zeta(3)^2/[4\zeta(2)\zeta(4)]\approx 0.391$ only extremely slowly with increasing particle number. We also show that ensemble effects are visible in the second-order correlation function $g^{(2)}(x)$ near the condensation crossover. After ballistic release from a three-dimensional harmonic trap, the time evolution of $g^{(2)}(x)$ preserves the differences between statistical ensembles.

The magnetic penetration depth, $\lambda$, is a fundamental parameter of the superconducting state and is commonly determined from precision measurements of the magnetic susceptibility, $\chi$, in the Meissner state. However, extracting $\lambda$ from such measurements requires an accurate treatment of geometry-dependent demagnetization effects, for which analytic results are only available in a limited number of cases. Here we present a finite-element analysis of the magnetic response of three dimensional superconducting spheroids and cylinders with finite penetration depth. By calculating the magnetic moment and susceptibility, $\chi(\lambda)$, over a wide range of aspect ratios, we quantify the shape-dependent Meissner response and extract effective demagnetization factors in the $\lambda \rightarrow 0$ limit. For small but finite $\lambda$, we further determine effective sample dimensions from the initial variation of $\chi(\lambda)$ and propose an improved analytical expression for these. Our results provide a high-precision procedure for determining $\lambda$ from volume-exclusion based susceptibility measurements and should be directly applicable to the characterization of novel superconducting materials.

Density functional theory (DFT) gives the electronic structure of materials, but its cost limits large-supercell calculations and materials screening. Machine-learned Hamiltonians bypass the self-consistent cycle but are usually system-specific; universal ones could cover new compositions and disordered solids. Such models must generalize across chemistry and keep downstream properties physical, while staying inexpensive for large cells. Here we introduce UniTB, a universal E(3) equivariant Hamiltonian representation framework that integrates physical priors rooted in density-functional tight-binding theory with deep learning. UniTB's network, which corrects a prior Hamiltonian, generalizes across chemistry through a mixture of experts routed by that prior and a charge-equilibration head as in self-consistent-charge tight binding. A projection bounds band shifts from the prior, suppressing spurious states and keeping downstream properties physical. We provide the fastest SO(2) tensor-product GPU kernels for the network. The variant UniTB-Flash assembles its prior from two-center tables at $O(N)$ cost for $N$ atoms, against $O(N\log N)$ on a grid. Trained on 29,242 crystals, UniTB reaches a 0.48 meV matrix-element error on nonmagnetic test crystals spanning 68 elements. Without amorphous training data, both models agree with DFT optics and conductivity of amorphous Ge-Sb-Te. UniTB-Flash ranks candidates with no significant difference from UniTB, whose property values are more accurate; together they screen 16,195 crystals for five application domains of industrial relevance.

Chemical pressure plays a critical role in determining the crystal structures and physical properties of intermetallic compounds. Here, we report the synthesis, crystal structure, and physical properties of Sm$_2$Ir$_8$Al$_{31}$, a structural analog of UIr$_4$Al$_{15}$, in which the smaller 5f uranium atoms are replaced by larger 4f samarium atoms. Single-crystal X-ray diffraction reveals a tetragonal $\sqrt{2}\times\sqrt{2}\times1$ superstructure with space group $P\bar{4}2_1m$, derived from a UIr$_4$Al$_{15}$-like average structure with space group $P4_2/nmc$. Comparison with UIr$_4$Al$_{15}$ shows that chemical pressure from U-to-Sm substitution produces a strongly anisotropic structural response rather than a uniform expansion of the Ir-Al framework. While one Ir coordination environment undergoes only modest changes, the other exhibits substantial local rearrangement. The Al sublattice primarily accommodates these structural distortions, with selected Al sites showing positional splitting, anisotropic atomic displacement ellipsoids, and partial occupancies, resulting in an Al-rich composition of approximately Sm$_2$Ir$_8$Al$_{31}$. Magnetic susceptibility measurements reveal a direction dependence, including a broad anomaly near 50 K for selected magnetic-field orientations. However, the absence of corresponding anomalies in heat capacity, electrical resistivity, and lattice parameters suggests that this feature is more consistent with an anisotropic magnetic crossover than a bulk thermodynamic phase transition. These results highlight how chemical substitution at the f-element site can induce Al-sublattice reconstruction and modify the magnetic response within a closely related Ir-Al structural framework.

High-throughput computational and generative approaches are proposing candidate materials far faster than they can be synthesized, making it increasingly important to identify which hypothetical materials are likely to be experimentally realizable. Positive-unlabeled (PU) learning has emerged as a representative framework for synthesizability prediction, yet existing approaches treat experimentally reported materials as a static collection, overlooking the historical trajectory of materials discovery and the diverse practical factors that have driven its progress. Here we introduce ChronoSyn, a chronology-aware machine learning model that jointly learns synthesizability and the relative reporting order of known materials through a shared composition representation. Incorporating discovery chronology provides additional supervision beyond conventional synthesizability labels, improving prediction performance and enabling ChronoSyn to identify experimentally realizable compositions more effectively than baseline models. Applied to approximately 50 million hypothetical compositions, ChronoSyn identifies chemically coherent high-scoring families that include experimentally reported compositions unseen during training. These results highlight the chronology of materials discovery as an informative learning signal and suggest that the path along which known materials were discovered can point the way to those that will be discovered in the future.

We compare the migration of a single Cr atom on monolayer graphene, between AB-stacked layers and between AA-stacked layers, with one first-principles protocol (PBE+D3(BJ), one cell family, registry anchors and spin-state search). We find three main results. First, on the surface and in the AB gallery Cr stays magnetic and moves almost freely. On the surface the C-C bridge is the minimum in 4x4 and 5x5 cells, and the highest point we sample on a hop lies 10 meV above it (5x5). In the AB gallery Cr sits on the inversion centres of the bilayer, which form a kagome net, and hops between them over 15 meV with a moment of about 4.32 $\mu_B$. Second, in the AA gallery the minimum is a nonmagnetic $\eta^6$-$\eta^6$ sandwich that pulls the layers together. Leaving it requires opening the gallery and switching Cr to a moment of 4-5 $\mu_B$, so we map the path with separately relaxed spin branches. The barrier estimate is 636 meV in a 3x3 cell but 260 and 185 meV in 5x5 cells with the far-field spacing pinned and free, and it is not yet converged. At 300 K, with equal prefactors and if the spin change is not rate-limiting, Cr hops between AA layers 3-4 orders of magnitude more slowly than between AB layers, using the 5x5 AA estimates and the 3x3 AB band. These AA numbers are specific to PBE+D3: an on-site U of 1.0 eV on Cr d already makes the magnetic states the AA ground state. Third, Cr binds 246-666 meV more strongly in AA than in AB registry, so the fast AB hop requires that the layers keep their Bernal registry around Cr.

We show that a class of pyrochlore materials provides a route to realize 3D Quantum Hall insulators, based on magnetic texture and flat band interference. We study itinerant electrons on a pyrochlore lattice Kondo-coupled to localized moments living on another interpenetrating pyrochlore lattice, with the moments forming a field-selected three-in/one-out texture. The noncoplanar texture generates complex spin-dependent hopping amplitudes and unequal local exchange energies, reconstructing the compact-localized parent flat bands into narrow bands separated by a global three-dimensional gap. The low-energy states are concentrated predominantly on kagome planes within the three-dimensional lattice, reflecting the combined effects of quantum interference and the texture-induced sublattice potential. When the lowest band is fully occupied, the response is characterized by a Chern triplet $\mathbf{C}=(1,1,1)$ and reciprocal Hall vector $\mathbf{G}_{\mathrm{H}}=(2\pi/a)(1,1,1)$, giving $\sigma_{yz}=\sigma_{zx}=\sigma_{xy}=e^2/(ha)$. The quantized bulk Hall response enforces chiral surface spectral flow, visible as noncontractible Fermi loops at the surface. Our work opens a new direction in the search for three-dimensional quantum Hall physics in magnetic pyrochlore systems, and suggests a broad design principle based on the interplay of magnetic texture and flat-band interference.

We present the experimental study of spin rectification in parallel and series networks of ferromagnetic conductors. The networks were composed of Ni36Fe64 elements (wires) which, when subject to ferromagnetic resonance (FMR), develop a small spin-rectification photovoltage. We found that the effect of spin rectification can be modeled as an increase in resistance of the ferromagnetic elements and closely follows the usual dependence of total network resistance in series and parallel electric circuits: the total spin-rectification photovoltage in ferromagnetic wires connected in series is equal to the algebraic sum of contributions from individual wires, while in the parallel connection one needs to add the reciprocals of the individual contributions. Our results support a simple way to control and manipulate the magnitude of spin-rectification photovoltage in multi-element spintronic devices.

Frustration in magnetic systems gives rise to unconventional orders and exotic spin liquids. Here, we explore a new type of frustration arising from an intrinsic bond-dependent orbital-field that couples orbital degrees of freedom to spin correlations. Introducing this orbital-field interaction into the antiferromagnetic Heisenberg model on the honeycomb lattice, we show that local spin-orbital constraints generate a subextensive degeneracy, lifted by order-by-disorder to select distinct collinear magnets in a cascade of phases as the orbital field increases from a para-orbital liquid. At larger fields, the selected phase gives way to an incommensurate unidirectional spiral that spontaneously breaks chiral symmetry. This transition is driven by the coupling of a Goldstone mode to gapped dynamical spin-orbital fluctuations. The spin stiffness becomes negative along a particular direction, while the spiral wavevector grows as the square root of the distance from the transition, signaling a Lifshitz-type transition. We present a microscopic route to realizing this orbital field and discuss candidate materials.

While coherent excitons have recently been observed to dress electronic states in time- and angle-resolved photoemission spectroscopy (tr-ARPES), exciton-driven dressing in optical spectroscopy remains largely unexplored. This work develops a theoretical and computational approach to exciton-driven dressing effects in transient absorption spectroscopy in the time-dependent adiabatic GW formalism and derives two symmetry- and band topology-protected selections rules for exciton-dressed transient absorption, unique from tr-ARPES. We then numerically calculate exciton-dressed transient absorption spectra of monolayer MoS2 and demonstrate the selection rules and their lifting after symmetry breaking.

Quantum computation offers a promising path towards efficient calculations of the electronic structure of correlated materials. The properties of iron-based materials, which are key for advancing geological and astrophysical understanding, are notoriously difficult to calculate with classical computers. However, despite the many recent advances in quantum computing on near intermediate scale quantum hardware, a full treatment of the electronic structure of high-$Z$ atoms or molecules remains challenging. Here, we investigate the ground-state properties of molecular FeO and Fe$_2$O$_2$ model Hamiltonians using classical exact diagonalization, Variational Quantum Eigensolver (VQE), and Sample-based Quantum Diagonalization (SQD). The experimental quintet ground state of FeO is recovered classically and with quantum algorithms, while a nonet ground state is recovered for Fe$_2$O$_2$. Although raw VQE does not achieve chemical accuracy for the ground state of FeO or Fe$_2$O$_2$, SQD with two connectivity shells recovers the exact ground energy for both molecules utilizing remarkably few quantum computational resources. Overall, our results indicate that $ab \; initio$-informed low-energy models of correlated materials, combined with SQD, offer a new alternative for scaling up calculations of ground-state properties of strongly correlated solids on existing quantum hardware.

Buried interfaces play a critical role in the operational stability of perovskite optoelectronic devices, yet remain challenging to probe non-destructively. Here, we demonstrate a multiwavelength photoluminescence-based approach exploiting the wavelength-dependent absorption of perovskites, enabling fast, and non-destructive probing of depth-sensitive degradation behavior of perovskite devices under operational conditions. Using ultraviolet (UV) light-soaking with different indium tin oxide (ITO) modifiers as a test case, we employ wide-field photoluminescence (PL) imaging, time-resolved photoluminescence (trPL) and ideality factor measurements with different wavelength excitation to characterize degradation behavior of both perovskite thin films and photovoltaic devices under UV soaking. Using only nondestructive characterization, we show that UV-induced degradation in p-i-n perovskite solar cells occurs preferentially at the HTL interface, adversely affecting device stability, consistent with ex-situ destructive tests. Our results also show that modifying the buried interface with 3-mercaptopropyltrimethoxysilane reduces UV-induced damage at the buried interface, thus improving the UV stability of both perovskite films and devices. This work establishes a fast, non-destructive strategy to screen depth-dependent degradation in perovskite devices, offering insights for interface design and stability optimization.

Barium Strontium Titanate ((BaxSr1-x)TiO3, BST) thin films are amongst the most extensively studied dielectric alloys over the last decade. This is due to the tunability of the dielectric constant and dissipation factor in the underlying ferroelectric and paraelectric states. One important feature of BST is that the competition between the ferroelectric BaTiO3 and the paraelectric SrTiO3 parent phases can be tuned by the A-site alloy concentration, opening a platform for exploring dielectric phase competition. However, the understanding of the interplay between and establishing the control of the dielectric phase from thin film deposition parameters has not been sufficiently reported in the literature. Here, we synthesized a series of SrRuO3/BST/SrRuO3 epitaxial thin film heterostructures by Pulsed Laser Deposition (PLD) from a (Ba0.9Sr0.1)TiO3 target under systematic variation of the oxygen partial pressure during the BST deposition. We mapped the dielectric phase of the film to the oxygen growth pressure, film composition, and film crystal structure. A ferroelectric, relaxor-like, or paraelectric phase can be obtained with relatively moderate change in oxygen growth pressure. Scanning transmission electron microscopy (STEM) analysis further indicates that this pressure-dependent phase evolution is accompanied by a structural transition of the BST lattice from tetragonal toward a nearly cubic phase, with the latter corresponding to the relaxor-like state. The control of the dielectric phase opens a pathway to study phase evolution and enable future computing technologies.

Swarmalators are particles which have internal degrees of freedom in the form of phase oscillators that can synchronize and change the dynamics of the particles. We explore the active matter disk swarmalator model proposed by Adorjáni [Phys. Rev. E 109, 024607 (2024)] where there is an additional attraction or repulsion determined by whether the phases of particles within a certain radius synchronize or anti-synchronize. This model in the absence of swarmalator rules forms a motility-induced phase-separated (MIPS) state at high activity, but when the swarmalator rules are present, a number of additional states appear including an active gel, labyrinth state, frustrated MIPS, and frustrated fluid states. Here we examine ratchet effects for the Adorjáni model coupled to asymmetric substrates. We find that swarmalator interactions can strongly enhance or suppress active matter ratcheting depending on the structural state of the system, and show that the ratchet efficiency depends on the substrate strength, substrate lattice spacing, and the motor force on the particles. The gel state exhibits the weakest ratcheting for small substrate spacing and can even produce a reversed ratchet motion, but shows the strongest ratcheting for large motor forces. The labyrinth state exhibits the strongest ratcheting over a wide range of parameters since the quasi-one-dimensional labyrinth morphology can match the substrate geometry well.

Filaments are incredible material building blocks that, when entangled together, form robust structures with remarkable adaptive mechanics, from stiff cables to stretchable knits. Basic questions about the mechanism that holds together such structures, especially assemblies like rope, without attractive physical or chemical bonds between constituents are among the oldest considered in materials science. Contradicting a long-standing picture that structural integrity of rope-like assemblies rely on a combination of external loading and inter-filament friction to prevent spontaneous detangling (e.g. fraying of a cut rope), we demonstrate that assemblies of intrinsically-curved filaments can achieve structural integrity purely from the competition of elastic forces that resist shape-change and (traction-free) repulsive forces that prevent overlap. We analyze a friction-free model of assembly of intrinsically-helical filaments, and show that depending on filament number and preferred filament shape, overcrowding in the assemblies generate elastic pre-stresses that give rise to either self-locking entanglement or spontaneous detanglement through propagation of a soliton-like detanglement front through assemblies. We test a generalized fracture criterion for spontaneous detangling and confirm the role of shape-elastic costs to self-locking via experiment and simulation of frictional filaments, demonstrating a range of bundled structures which cannot be made self-locking for any value of friction. The mechanism of ``purely elastic cohesion" illuminated here sheds light on self-locking in a broader class of entangled structures, and further, offers design principles for new classes of active filament materials capable of stimuli-responsive assembly and disassembly.

The superconducting diode effect (SDE) is characterized by unequal critical current magnitudes for opposite-polarity current flow, owing to broken spatial-inversion and time-reversal symmetries. For a superconducting pair wavefunction to spontaneously break inversion symmetry implies the formation of Cooper pairs with nonzero momentum, yielding a nonuniform superconducting state. For singlet superconductors, the formation of such a (FFLO) state has long been understood to provide an escape from high field Pauli pair-breaking -- how and why such an effect might occur for equal spin pairing is an open question. Here we report the observation of a large SDE in bulk specimens of the three-dimensional heavy-fermion triplet superconductor UTe$_2$, with a peak diode efficiency of 33% at the high magnetic field strength of 33.6 T, representing the highest-field observation of the SDE to date. Crucially, this nonreciprocal transport is strictly confined to a narrow field regime where superconductivity coexists with a field-induced spin-polarized state near a first-order metamagnetic phase boundary. The absence of the SDE away from this slender phase-intersection argues strongly against purely extrinsic vortex pinning asymmetries. Instead, our findings indicate spontaneous inversion symmetry breaking accompanied by finite-momentum Cooper pairing. We model this behavior using a phenomenological Ginzburg-Landau theory, demonstrating that the intertwining of magnetic and triplet superconducting orders can stabilize an odd-parity FFLO state.

Unconventional superconductors with a two-component order parameter support the existence of a rotational symmetry breaking nematic phase and a time-reversal symmetry breaking chiral phase. A recent experiment on 4Hb-TaS$_2$ surprisingly shows both twofold anisotropy in $H_{c2}$, which suggests nematic superconductivity, as well as isotropic vortices at low temperatures, which suggest chiral superconductivity. To resolve this apparent conundrum we write down the appropriate Ginzburg-Landau equations and develop a numerically efficient algorithm for finding vortex solutions, allowing us to study their shape and anisotropy over a broad parameter range. We also demonstrate analytically that, to leading order, the vortex anisotropy is independent of strain in the nematic case, but is linearly dependent on it in the chiral phase, providing a possible way to distinguish the two phases. Using all these results we show that, in the presence of strain, in a large parameter regime the system behaves nematically near the transition, leading to an anisotropy of $H_{c2}$, but is dominantly chiral away from the transition, leading to parametrically smaller vortex anisotropy, in line with the experiment.

We report electrical tuning of spin relaxation in atomically thin $T_{\rm d}$-MoTe$_2$, a representative low-symmetry transition metal dichalcogenide. Weak antilocalization measurements reveal strong spin--orbit interaction with spin--orbit lengths of tens of nanometers, consistent with recent theoretical predictions. Despite the semimetallic nature of $T_{\rm d}$-MoTe$_2$, in the ultrathin limit the spin--orbit scattering time can be tuned electrostatically by up to threefold. We further investigate vertical electric field effects on the spin--orbit length and time, and demonstrate the modulation of the Rashba parameters. Relation between spin--orbit scattering time and the diffusion coefficient indicates that spin relaxation is governed by the D'yakonov--Perel' mechanism in both monolayer and bilayer $T_{\rm d}$-MoTe$_2$. These results establish few-layer $T_{\rm d}$-MoTe$_2$ as a platform for electrically tunable spin transport, thereby providing insight into spin relaxation in low-symmetry transition metal dichalcogenides.

The Buice-Cowan field theory [PRE 75, 051919 (2007)] describes fluctuations and correlations of neural activity through a path integral whose mean-field limit is the Wilson-Cowan equation and whose critical behavior belongs to the directed percolation class. In its continuum limit the neurons are the points of a Euclidean space and activity spreads by ordinary diffusion, which encodes neither the hierarchical organization of cortical networks nor their small-world property. We formulate a version of the theory in which the neurons are organized in an infinite, self-similar, tree-like structure, described by the p-adic numbers. The path integral carries over unchanged, and finite networks are exact restrictions of the continuum theory. The main change is in the linear response: in the Euclidean theory every short-range kernel reduces to the Laplacian, while in the p-adic theory each connectivity kernel gives its own nonlocal p-adic diffusion operator. For couplings that decay by a fixed factor per level of the hierarchy this is the Taibleson-Vladimirov operator, and the critical theory is an ultrametric Reggeon field theory whose upper critical dimension is twice the decay exponent of the coupling. Hence the decay of the coupling up the hierarchy, and not the dimension of space, decides whether mean-field exponents apply. We obtain a Ginzburg-type criterion, loop-corrected hierarchical Wilson-Cowan equations, log-periodic corrections to scaling and power-law correlations. Exact simulations on a tree support the predictions: the avalanche-size exponent takes the mean-field value 3/2 when the coupling decays slowly and decreases toward the directed-percolation value when it decays fast. The hierarchical network is also small-world when the decay exponent is smaller than the dimension, a property that the Euclidean theory obtains only by assuming long-range coupling.

Neural avalanches with size exponent $3/2$ are usually explained by mean-field critical branching, which for short-range coupling requires dimension $N\ge4$. We show that hierarchical connectivity removes this constraint. In a $p$-adic version of the Buice--Cowan field theory, a coupling that decays by $p^{-(N+\sigma)}$ per hierarchical level selects the Taibleson--Vladimirov operator, and the critical theory is ultrametric directed percolation with upper critical dimension $N_c=2\sigma$. Exact simulations on a tree give $\tau_S=3/2$ for $\sigma\le N/2$, decreasing continuously for $\sigma>N/2$.

We develop rotational perturbation theory for magnetic interactions in collinear and noncollinear systems, distinguishing prescribed rotations of exchange fields from constrained rotations of magnetic moments. At the full exchange splitting, we derive Green-function expressions for prescribedfield energy curvatures directly from perturbation theory, without invoking the local force theorem; constrained-moment curvatures additionally require the stationary magnetic response and are related to the inverse static susceptibility. We examine noncollinear pair interactions and planar and conical spin spirals, and derive the long-wavelength ferromagnetic spin-wave stiffness and, assuming adiabatic sublattice precession, the antiferromagnetic spin-wave velocity. Orbital-nonlocal magnetic potentials and correlated electronic response reveal further requirements for connecting rotational curvatures to collective magnetic behavior. As a practical extension, we project the complete transverse pair Hessian onto an effective scalar Heisenberg exchange and quantify the unreconstructed curvature. Biquadratic and three-spin examples illustrate why locally extracted exchange coefficients need not represent transferable bilinear interactions.

Kirigami-inspired cuts are an established route to stretchability in two-dimensional materials. At the nanoscale, however, cut edges are not purely geometric: they comprise discrete atomic configurations that can alter the mechanical response. In graphene, a given cut geometry fixes the edge structure; graphyne, a porous carbon allotrope with an intrinsic band gap, lifts this constraint, as identical cut geometries can yield distinct hole-edge configurations. Using molecular dynamics simulations, we report the first atomistic study of $\gamma$-graphyne kirigami (GYK), and compared with graphene kirigami. GYK reaches yield strains up to 9.6 times that of pristine $\gamma$-graphyne, with a response governed by both cut geometry and local hole-edge structure. Removing just two carbon atoms at selected edge sites further raises the yield strain by up to 35%, with little loss of yield stress. These findings identify hole-edge atomic configuration as an additional design parameter, expanding the design space for nanoscale kirigami engineering.

To address the complex interplay of microstructural evolution, phase separation, superconductivity coherence and quantum fluctuations, we prepared Cuxwt%Nb series of granular samples by rapidly cooling, where the niobium concentration varied (x = 3, 5, 15, 20). By employing this method, we successfully obtained samples characterized by well-defined precipitates of niobium, featuring regular sizes and grain spacing. The goal was to establish a systematic and robust method approach for obtaining samples with different of sub-micrometric precipitates distributions but also to investigate their superconducting properties. Structural characterization by optical and Scanning Electron Microscopy, dc Mdc[H,T] ac inductive , as well the magneto-transport measures rhodc[H,T], Rdc[V,I.H,T], I[V,H,T] and [H,T,I] were done. Also, using a micro Hall sensor with 10 measuring transverse voltage bridges regularly distributed, we were able to obtain the real external applied magnetic field value inside of the chamber sample space. Thus e studied the dependence of configuration of the Nb grains in the superconducting coupling order parameter properties that connects the grains superconductors to the normal Cu matrix. We verify through magnetization and transport measures the signature of the double transition. This, when we apply current of different intensities, in the transport measures, and different field values, in the inductive measures. This behavior is an indication that our system is made up of by a collection of superconducting grains immersed in a well-organized in a non-superconducting matrix. The results indicate that the superconducting properties of these systems are manifested usually through two transition temperatures Tc(H) e TcJ(H).

Nanoparticle self-assembly offers a powerful route to programmable functional materials, but its dynamics remain difficult to understand because they arise from multiscale, many-body, and environment-dependent interactions. Liquid-phase transmission electron microscopy (LPTEM) enables real-time observation of these dynamics, yet extracting the underlying physical laws from highly stochastic trajectories remains a significant challenge. Here we develop a physics-informed, time-varying autoregressive framework that learns multiscale self-assembly dynamics directly from LPTEM videos. Continuous Eulerian fields with local density and orientational order are coarse-grained from individual video frames and evolved by a sparse, nearest-neighbor operator optimized over a constrained matrix manifold. This interpretable approach captures long-time large scale phase transitions by tracking operator volatility over time, and short-timescale local evolution and transport rules. Crucially, we extract the underlying partial differential equations, where expected symmetries naturally emerge, enabling the direct inference of fundamental coefficients. Our framework provides a robust, computationally efficient tool for discovering hidden physical mechanisms from observational data, opening a path toward the predictive design of self-assembled nanostructures.

The formation of topological flat bands near the Fermi level in kagome-structured metals has generated substantial research interest. One key consequence of this electronic structure is the strong anisotropy in charge transport, such as the significantly higher in-plane resistivity relative to the out-of-plane direction. However, the spin transport properties of these flat-band kagome metals are still largely unexplored. In this work, we investigate spin-charge conversion in CoSn, a representative flat-band kagome metal. Scanning tunneling microscopy is employed to image the CoSn surface with atomic resolution, and $dI/dV$ spectroscopy shows clear signatures of the flat bands. Using magneto-optical techniques, we quantify the spin-orbit torque (SOT) in bilayers of ferromagnetic nickel (Ni) and c-plane CoSn thin films. We find a large effective spin Hall angle of $\theta_{SH} = 0.484 \pm 0.005$ within the CoSn layers, significantly exceeding the value measured for Pt of $\theta_{SH} = 0.0436 \pm 0.0003$ in Ni/Pt bilayers. Density functional theory (DFT) calculations provide a microscopic understanding of the intrinsic spin Hall effect in CoSn, elucidating the sources of Berry curvature in momentum space. These findings establish kagome metals as promising materials for efficient spin-charge conversion and low-power spintronics.

We apply the Constructive Cavity Method (CCM) to the dense, Ising type, restricted and deep Boltzmann machine with Gaussian couplings between adjacent layers. After identifying the core and interface contributions, CCM identifies the blanket decomposition of the cavity variables with the Aizenman--Sims--Starr random overlap structure. We apply the Random Energy Model (REM) universality ansatz to represent the cavity free energies by those of a generalized random energy model (GREM) and evaluate them recursively through Poisson point processes (PPPs). In the layer-wise gauge each layer is cut with its own cumulative fraction $|U_\ell\cap L_p|=\lambda_p q_\ell^{(p)}N+o(N)$, with $\mathbf 0=\mathbf q_0\le\mathbf q_1\le\cdots\le\mathbf q_r=\mathbf 1$, where $\mathbf q_\ell=(q_\ell^{(1)},\ldots,q_\ell^{(K)})$. Here $U_\ell$ is the cumulative blanket union up to blanket $\ell$. The index $p$ labels architectural layers, whereas $\ell$ labels the blankets. The dependence on the multilayer geometry is carried by the two matrices $M=2M_0\Lambda$ and $M_1=\Lambda M_0\Lambda$. The constructive cavity field in layer $p$ has blanket variances $Q_\ell^{(p)}-Q_{\ell-1}^{(p)}=(M(\mathbf q_\ell-\mathbf q_{\ell-1}))_p$, while the correction field has blanket variances $Q_\ell-Q_{\ell-1}=\mathbf q_\ell^\top M_1\mathbf q_\ell-\mathbf q_{\ell-1}^\top M_1\mathbf q_{\ell-1}$. The nested REM--PPP average gives the finite-level constructive cavity functional $\mathcal{P}_{\mathrm{RBM/DBM}}^{\mathrm{CCM}}(\zeta,\mathbf q)=\log2+\sum_{p=1}^K\lambda_pX_0^{(p)}-\frac12\sum_{\ell=0}^{r-1}\zeta_\ell(\mathbf q_{\ell+1}^\top M_1\mathbf q_{\ell+1}-\mathbf q_\ell^\top M_1\mathbf q_\ell)$. The balanced scalar gauge is recovered by imposing $\mathbf q_\ell=q_\ell\mathbf 1$. Selecting the physical value in the non-convex multilayer regime is a separate problem.

Gauge-Higgs theory in flat spacetime provides a prime theoretical model of multiple phases of matter with distinct entanglement structures. More recently, there has been interest in hyperbolic space and the influence its extensive boundaries have on these structures. Entanglement transitions between non-equilibrium phases, such as topological phases, can be realized by the competition of non-commutating measurements. Here we study the entanglement phases of gauge-Higgs models on hyperbolic lattices described by measurement-only dynamics. We chart 2D phase diagrams by employing topological entanglement entropy and introducing a generalized measurement-induced entanglement tailored for hyperbolic Higgs phases. Utilizing duality, we find a phase absent in Euclidean space, wherein the bulk lattice hosts separated clusters of symmetry-protected topological order. Transitions between this "archipelago" phase and neighboring topological and trivial phases feature a critical exponent $\delta$ belonging to a mean-field universality class. Our essential tool is a 3D resource state inspired by measurement-based quantum computation that simulates the spacetime evolution of the 2D quantum state with a third direction of entanglement. This allows us to analyze spacetime "sponges" of entanglement, which map to classical percolation theory and allow us to infer values of critical points on our phase diagrams' boundaries.

Magnetoresistive sensors with multiaxial sensitivity are interesting for field mapping applications where local measurement of multiple magnetic field components is needed. Existing device designs are often discretized with separate sensing elements for each vector component, or they require complex detection schemes to distinguish the different components. In this work, we showcase a single-element two-dimensional vector sensor with on-demand reprogrammable sensing axis using light and optically switchable materials. Our device is an anisotropic magnetoresistive sensor with $90^\circ$ togglable sensitivity upon excitation with ultrashort laser pulses. The sensor consists of an optically switchable Co/Gd thin-film bilayer, patterned into a cross shape that stabilizes two orthogonal in-plane magnetization directions. By selectively addressing one diagonal of the cross, a single laser pulses toggle switches the magnetization direction in the center of the cross by $90^\circ$. Moreover, the field sensitivity of the device is toggled between the $x$- and $y$-axes, which we detected electrically with the planar Hall effect. Our results form a milestone towards optically reprogrammable integrated magnetic vector sensors.

Topological spin textures such as skyrmions and bimerons offer rich physical functionalities and strong potential for future spin-based technologies. Identifying materials that host such emergent magnetic states, however, remains challenging due to the complex interplay between microscopic magnetic interactions and large-scale spin textures. Here, using a multiscale first-principles discovery framework, we identify a broad class of two-dimensional materials that stabilize nontrivial spin textures. The framework integrates relativistic density functional theory, magnetic force theory, and atomistic spin-dynamics simulations, enabling a direct connection between electronic interactions and emergent magnetic textures and allowing efficient screening of systems with large magnetic unit cells and competing exchange interactions. Applying this approach, we systematically screen 312 monolayer transition-metal dichalcogenides across 1T and 2H phases of 3d, 4d, and 5d transition metals. We uncover a diverse set of emergent spin textures, including skyrmions, bimerons, and complex domain states, and clarify their distinct stabilization mechanisms driven by exchange interactions, Dzyaloshinskii-Moriya interactions, and magnetic frustration. These results identify promising candidate materials for topological spin textures and establish a transferable computational framework for accelerating materials discovery of complex magnetic states in two dimensions.

Mobile anyons in topologically ordered phases provide a setting to investigate how fractional exchange statistics shapes collective behavior at finite density. We introduce AnyFormer: a neural variational framework for continuum anyons on a torus that explicitly incorporates statistical interactions and global winding constraints. We construct a smooth orbital frame that enforces the matrix-valued torus boundary conditions, and supplement it with an analytic pair factor that supplies the regular collision behavior. The orbital geometry and many-body amplitudes are optimized in parallel by variational Monte Carlo. We apply AnyFormer to semions without an external field or interaction potential, isolating unique correlations generated solely by statistics. Our framework closely matches exact two-semion energies and yields lower variational energies than finite-cutoff exact diagonalization for $N = 4$ and $6$ semions. Scaling up to $N = 16$ semions, well beyond the limits of continuum diagonalization, our calculations reveal states with pronounced correlation holes, suppressed long-wavelength density fluctuations, and a reversal of pair circulation at a distance set by the mean particle spacing. For $N = 12$ and $16$ semions, the circulation develops damped spatial oscillations. AnyFormer thus provides a scalable variational neural-net framework for microscopic studies of correlations, chiral motion, and collective phases of bulk anyonic matter.

We study the propagation of ferrons, the quanta of electric polarization waves, through a ferroelectric texture. We predict by analytic and numerical calculations that a $90^\circ$ domain wall (DW) operates as a beam splitter of longitudinal ferron and transverse optical phonon modes. An associated momentum-flux imbalance leads to forces that drive DW motion. In the weak-anisotropy limit, the DW becomes a rotating texture with nearly fixed-modulus, whose low-energy dynamics is described by a sine-Gordon equation. A ferron source then attracts the DW through a damping-induced force. Both driving forces scale linearly with incident wave intensity. Our results uncover qualitatively different routes to driven ferroelectric DW motion enabled by the vector nature of the polarization and offer functionalities for THz ferroelectric devices.

Zr cladding alloys in nuclear reactors are exposed to high neutron fluxes, making irradiation-induced defects and solute segregation central to understanding their in-service behaviour. Dislocation cores involve short-range chemistry and long-range elastic fields, which are difficult to describe simultaneously using conventional atomistic methods. Using a hybrid quantum mechanics/machine learning (QM/ML) framework, this part of work examines prismatic <a> loops in hcp {\alpha}-Zr. All three loop variants are considered, including faulted and perfect, interstitial- and vacancy-type, and first- and second-order prismatic configurations. Nine possible dislocation line segments are characterised in terms of core geometry, solute binding, glide barriers and faulted-to-perfect transition pathways using QM/ML and newly implemented QM/ML-NEB calculations. Shockley and half-Shockley partials, together with basal and prismatic fault ribbons, are found to govern core stabilisation. Fe and H preferentially bind to faulted segments, whereas Sn and Nb favour perfect segments. Solutes can also drive partial motion, recombination and local unfaulting. These results establish a comprehensive picture of <a> loop microstructure, solute trapping and transition mechanisms in {\alpha}-Zr.

Translating macroscopic mechanical concepts such as gears to the molecular scale offers a route to precise control over nanoscale motion, inspired by the efficiency of biological machines. In this work, we explore two-dimensional interlocked linker rotations in the flexible metal-organic framework NU-2002. The volume-dependent free energy landscape is mapped using bias-deletion metadynamics to identify six characteristic phases, ranging from very closed to very open pore. We then perform unbiased molecular dynamics simulations at each phase to track rotation events and evaluate co-rotation statistics, calculate free energy barriers, and measure pairwise radial force transfer between neighbouring linkers. We show that the free energy barrier acts as a rotational-speed filter, where rare rotational transitions lead to higher speeds on average. Across the volume profile, we classify four distinct geared regimes: sterically restricted rotations at small volumes (Jammed Gear), rotational coupling extending to third neighbour linkers (First Gear), in-plane partnered linker coupling (Second Gear), and uncoupled, independent rotation at large volumes (Neutral Gear). Together, these results establish framework breathing as a molecular gearbox that switches both the speed and collective coupling of linker rotation. Framework flexibility therefore offers a handle for programming collective motion in solid-state molecular machines.

Anion redox in Li-rich layered oxides places holes on oxygen next to an antiferromagnetic Mn(IV) d3 lattice, a strongly correlated open-shell problem for which projection-based wavefunction-in-DFT embedding offers a route to correlated and quantum solvers, but whose errors are known mainly for closed-shell molecules. We develop a spin-unrestricted projection-based embedding, exact at the DFT-in-DFT level to the microhartree scale for closed-shell, broken-symmetry and high-spin references with point charges, and apply DMRG-in-DFT to point-charge clusters of delithiated Li(2-x)MnO3, varying the environment functional (0-100% exact exchange), geometry, active region, active-space spin, virtual space, cluster size and magnetic reference. In every setting the lowest SCF state places the hole on an oxygen pair, with no O-O bond. How the hole is shared depends on the functional together with the geometry: hybrids give a full, uncoupled hole at the DFT+U geometry but a partial, weakly covalent hole at their own geometry, a change of up to 0.5 e on one oxygen. Where spin spreads across the active/environment boundary, the integer spin projection of the active space becomes a choice worth up to 0.26 e, and at most 0.09 e once the two Mn neighbors are included. An extended state search found missed lower states for two functionals, changing a pair-oxygen spin by up to 0.45 e. Across all 82 runs the embedded mean field gives the same hole (median DMRG change 0.02-0.04 e); correlation mainly adds O-O covalency. State control and geometry consistency, not the solver, dominate the uncertainty, and total energies are not converged at 30-40 orbitals. For quantum solvers, the embedded Hamiltonian must be spin-unrestricted: a shared-orbital form reverses the hole, while sample-based quantum diagonalization reproduces exact diagonalization, as accurately as, but not better than, classical selected CI.

We investigate the nonequilibrium dynamics of a kinetic slush state realized via facilitated excitations in a two-dimensional dissipative Rydberg atom array. Utilizing kinetic Monte Carlo simulations in the strong dephasing regime, we show that tuning the laser detuning to compensate for nearest-neighbor interactions enables facilitated dynamics, while residual next-nearest-neighbor interactions induce kinetic frustration. This competition gives rise to an emergent slush phase characterized by pronounced dynamical heterogeneity and the coexistence of liquid- and solid-like configurations. By probing its nonequilibrium real-time evolution, we uncover a dynamical crossover from isotropic spreading to one-dimensional constrained growth, which can be continuously tuned by the frustration strength. Within this crossover regime, the slush dynamics generate fractal cluster geometries and generalized Ornstein-Zernike spatial correlations. Finite-size scaling analysis supports the system's proximity to criticality. Our findings establish driven-dissipative Rydberg systems as a highly controllable platform for engineering complex nonequilibrium soft-matter phenomena.

What is the intrinsic reason of emergence of macroscopic order parameter out of microscopic systems? In this article, we apply to physics the collective predictive coding (CPC), the theory of language/symbol emergence. As our language emerges out of our human communications, physical macroscopic order parameter emerges out of communications among atoms --- each atom is regarded as an agent who predicts each other's behavior through inference. We present three examples of classical spin systems: two-dimensional ferromagnetic and antiferromagnetic Ising models, a two-dimensional spin model with competing stripe orders, and the fully connected Sherrington--Kirkpatrick spin-glass model. In all of these examples, proper macroscopic order parameters including the replica overlap emerge automatically through communication informatics of CPC, only from observed spin configurations. We call the learned macroscopic coordinate the collective predictive order. Furthermore, for the ferromagnetic and antiferromagnetic Ising models, the equilibrium distribution of the collective predictive order yields an emergent potential with the symmetry and thermal evolution characteristic of a Landau potential. Notably, the emergence of the collective predictive order does not refer to any structure of microscopic Hamiltonians/Lagrangians. Thus our ``Atom-as-an-Agent" (AaaA) principle offers a completely data-driven method for the emergence of macroscopic order, that is, machine learning physics.

Recent anyon-collider experiments have identified time-domain braiding (TDB) as a new route to probing anyonic statistics. However, how such time-domain interference responds to environmental noise remains an open question. Here we show that TDB interference is intrinsically more robust than its spatial counterpart. In conventional spatial interference, environmental noise induces phase fluctuations that accumulate throughout all paths, leading to exponential suppression of the interference as the dephasing rate increases. In TDB, by contrast, the interfering temporal paths experience largely overlapping environmental fluctuations, whose contributions cancel out in the relative phase, so that only a small nonoverlapping temporal window contributes to dephasing. As a result, TDB interference decays only algebraically with the dephasing rate, providing a new experimental hallmark for its identification. We propose a Fabry-Perot fractional quantum Hall setup in which both types of interference coexist and experience the same environmental noise, enabling a direct comparison of their dephasing behaviors. Our results establish robustness against dephasing as a fundamental advantage of TDB and suggest new opportunities for exploiting anyonic interference in noisy mesoscopic systems.

Microscale damage poses a significant challenge to the reliability and longevity of miniaturized photonic devices; however, the mechanisms and repair of microscopic cracks and fractures in organic optical crystals remain largely unexplored. Here, we employ a mechanophotonic approach to induce microscale cracks and complete fractures in single crystals of 3-[4-(dimethylamino)phenyl]-1-(2-hydroxyphenyl)prop-2-en-1-one (HDMAC) using an atomic force microscopy (AFM) cantilever tip. We demonstrate the self-healing capability of these crystals while retaining their optical waveguiding and resonator properties, which are essential for lasing applications. HDMAC microcrystals exhibit self-healing of cracks introduced along the (010) and (001) crystallographic planes, demonstrating the versatility of this phenomenon across distinct crystal orientations. Furthermore, we identify different fracture mechanisms and establish a comprehensive assessment of healing efficiency by integrating optical loss measurements, resonator characteristics, and nanomechanical analyses. This multifaceted approach enables fair evaluation of the recovery of structural integrity and photonic functionality following self-healing.

Solid oxygen is an $S=1$ molecular magnet with strong coupling between spin and lattice degrees of freedom. Recent studies suggest that magnetic moments coexist with tetramer distortions under pressure. We derive an effective spin Hamiltonian from a two-orbital Peierls--Hubbard model with spin-orbit coupling. The resulting model contains competing easy-plane single-ion and easy-axis exchange anisotropies. We analyze this model on a square lattice using quantum Monte Carlo simulations and evaluate the magnetic contribution to the lattice stiffness for several lattice distortion patterns including the tetramer pattern. We find that the tetramer pattern is the most favorable among the considered distortion patterns throughout the parameter range studied. Moreover, competition between the two anisotropies enhances the tendency toward lattice distortion and strengthens the preference for tetramerization over the other patterns.

Photon-magnon synchronized modes (PMSMs) provide a route for magnetic-field sensing by exploiting their enhanced field responsivity due to cusp points (CPs). However, the previous PMSM magnetometer relies on bulky discrete components and lacks in situ control of photon-magnon interactions, limiting its integration and adaptability. Here, we demonstrate a miniaturized PMSM magnetometer integrated on a printed circuit board. A variable resistor is used to tune the photon-magnon coupling strength in situ. By adjusting the variable resistor, the electromagnetic boundary condition of the magnetometer is altered; hence, the reservoir-mediated photon-magnon interaction is changed. The coupling strength shows a non-monotonic dependence on the reflection coefficient adjusted by the variable resistor and reaches its minimum at the impedance matching condition. Furthermore, we develop a non-Hermitian model with standing-wave interference to describe the PMSM dispersion and derive the critical condition for CP formation. This work realizes a compact and tunable PMSM magnetometer and provides a pathway for controlling photon-magnon interactions in integrated magnetic sensing systems.

We investigate the interaction and dynamics of vortices belonging to different components of a binary uniform quantum liquid. Using the coupled extended Gross-Pitaevskii equations with logarithmic beyond-mean-field corrections, we derive the asymptotic interaction potential between well-separated vortices. The interaction potential retains the asymptotic form $s^{-2}$ as a function of the intervortex distance s, but its coefficient depends on the background density through the quantum fluctuation. As a result, the interaction between vortices changes from attractive to repulsive at a critical density. Real-time simulations demonstrate a corresponding reversal of orbital motion of a vortex pair from clockwise to counterclockwise, consistent with their Magnus response.

Super-Bloch oscillations (SBOs) offer a powerful route to control wave packet propagation in driven lattices, yet their realization in magnonic systems has remained elusive. Here, we predict SBOs of magnon wave packets in periodic magnonic crystals driven by static and ac gradients of magnetic anisotropy field. A static gradient alone induces magnon Bloch oscillation (BO) with a constant carrier frequency. Remarkably, adding a near-resonant MHz-scale ac driving gives rise to a slow large-amplitude envelope oscillation, the hallmark of SBO. At exact resonance, the ac driving enables phase-controlled directional transport with a carrier-frequency shift up to GHz scale. Consequently, the same structure can be switched among three distinct regimes: conventional BO, SBO, and directed transport. Analytical expressions for the oscillation amplitudes, superperiod, drift velocity, and frequency evolution are validated by micromagnetic simulations. Extending to antiferromagnet magnonic crystals, we further demonstrate that these effects drive opposite motions of two oppositely polarized magnon modes in THz range. Our work establishes magnon SBOs as a versatile platform, opening a new avenue for reconfigurable magnonic devices.

Turning a flat-band parent into an isolated Chern band requires supervise of destructive interference, hopping phases, and the cell translations of the bonds. We study this connection in a seven-orbital 2 times 2 supercell honeycomb-vacancy lattice, combining analytic reductions with Bloch spectra, lattice Chern invariants, and quantum geometry. The parent lattice has three exact flat branches, a smooth periodic zero mode, and a compact localized state. A uniform gap bound shows that faint intracell-loop hopping preserves two topologically trivial insulating gaps. The intracell hopping graph also admits a staggered chiral coloring: reversing site amplitudes according to this coloring links opposite energies at momenta separated by half a reciprocal period. This constraint restricts the isolated central band to even Chern numbers and forbids a zero-energy insulating filling at every loop phase. Purely imaginary loop hopping admits a real gauge, whereas other phases allow paired band contacts connecting central bands with C3=2 and C3=4. On a specified strong-loop cut, third-order masses open the direct gaps; these gaps shrink faster than the bandwidth as the coupling grows. Changing the bond connectivity to an oriented honeycomb next-nearest-neighbor extension generates a narrower Chern band with nonuniform quantum geometry. These results distinguish individual-band topology from occupied-group topology and reveal how bond connectivity and cell translations determine which topological bands can emerge from an exactly flat parent.

Magnetic energy gaps do not reveal the spatial distribution of magnetic-state-dependent atomic forces. We compare ferromagnetic and antiferromagnetic forces at identical nuclear positions in 64-site substitutional Mn-doped Ge using collinear PBE calculations. For nearest-neighbour Mn pairs, the radial force projection reverses sign between magnetic branches. In the second-neighbour geometry, the shared Ge neighbour has the largest force contrast, about 2.2 times that of equally near Ge sites coordinated to one Mn. Bridge-displacement gap slopes agree with direct force derivatives across four numerical settings. Tightening the electronic threshold by 100-fold preserves magnetic ordering and the leading site, while the force-contrast vector changes by 1.08% despite a nearly unchanged energy gap. The results identify coordination-associated localization of magnetic-branch force contrasts within the frozen model, without establishing relaxed distortions, full numerical convergence or a unique exchange mechanism.

A thermopower that turns a temperature gradient into a perpendicular electric field in every in-plane direction has relied on magnetism. Reciprocity permits it without magnetism, yet under a three-fold or higher axis it vanishes both in reciprocal elastic band transport and in composites of two isotropic phases with ideal interfaces. Here we show that composites of three isotropic phases carry it, and that under such an axis three is the minimum. A third, linearly independent transport matrix escapes the exact two-phase reduction; at weak contrast the first allowed axial term is cubic, proportional to a determinant of the three matrices times material-weighted, handed three-point correlations. Treating the phases as colours identifies the arrangements that allow the response, and crystal nets from reticular chemistry supply printable three-dimensional ones. Certified two-sided bounds give axial Seebeck coefficients of 49.5-50.2 $\mu$V K$^{-1}$ in a planar cell and 76-84 $\mu$V K$^{-1}$ in a printable woodpile; reflections in planes containing the axis reverse the response, and recolouring 24 nets to restore their parent symmetry switches it off. Around a line heat source the axial driving field has the $1/r$ azimuthal form of the magnetic field of a straight wire and drives circulating currents.

Tribocharging of granular materials is a widespread phenomenon ranging from volcanic eruptions and dust storms to pharmaceutical processing, yet its underlying mechanism remains elusive. Recent thermoelectric models have provided a quantitative framework for triboelectric charge transfer, but they have difficulty accounting for charging between identical materials. In this Letter, we propose a theory of granular tribocharging based on the interplay between particle geometry and thermoelectric response. Collision-induced frictional heating produces a size-dependent temperature asymmetry between particles, generating a thermoelectric voltage that drives charge transfer. The sign of the Seebeck coefficient determines the charging polarity, while particle size and thermal properties set its magnitude. Our multi-collision theory explains the experimentally observed size- and material-dependent reversal of charging polarity, as in quartz and nylon.

Ground-state electron density contains sufficient information to determine ground-state energy, while providing spatial electronic information. This study developed a charge-density-informed graph neural network (hereafter CDGNN) that jointly learns energy and valence electron density from equivariant atomic graphs. This approach incorporates density-supervised real-space probe representations into the global energy regressor, allowing density-related spatial information to contribute to energy prediction. On the QM9 dataset, CDGNN reduced the energy prediction errors relative to an equivariant GNN baseline for interpolation and extrapolation to larger molecules. For small H-containing Fe and Fe-C datasets, CDGNN performed similarly to the baseline, indicating the dataset-dependent benefits of density supervision. CDGNN also accurately predicted the charge density distributions for molecular and Fe-based systems. The attention analysis showed higher weights for probe representations near the H atoms in Fe-based structures. These findings highlight the potential of integrating charge-density information for energy prediction and its task-dependent benefits.

Exciton-phonon coupling (ExPC) governs energy relaxation and exciton dynamics in photoexcited quantum materials. Recent advances have revealed rich and tunable excitonic phenomena in moiré superlattices, yet the microscopic mechanisms underlying the coupling between moiré excitons and moiré phonons remain elusive. Here, we develop a real-space representation for moiré ExPC based on a unified theoretical framework combining the many-body Bethe-Salpeter equation with phonon perturbation theory. Furthermore, we uncover a general real-space selection rule: the spatial matching of a moiré exciton's electron and hole densities with the moiré-phonon-induced potential perturbations determines their individual coupling contributions, while coherent interference between the electron and hole contributions controls the total ExPC. We demonstrate this rule in prototypical WSe2/WS2 moiré heterobilayers, revealing pronounced exciton- and phonon-mode-dependent coupling, including nearly complete suppression of ExPC through destructive electron-hole interference. These findings establish the internal electron-hole spatial configuration of moiré excitons as a key degree of freedom governing the strength and mode selectivity of their coupling to moiré phonons, opening opportunities to engineer ExPC through spatially tailored moiré potentials.

In rare-earth compounds, the interplay between geometric frustration and unusual single-ion anisotropy caused by the crystal electric field often leads to exotic magnetic phases. Here, we investigate the magnetic properties of the rare-earth Shastry-Sutherland compound Er$_2$Be$_2$GeO$_7$ using bulk measurements and neutron scattering down to sub-Kelvin temperatures. A $k=(0,0,0)$ stripe-like antiferromagnetic order with locally tilted Er$^{3+}$ moments is revealed by time-of-flight neutron powder diffraction, accompanied with a $\lambda$-shape specific-heat anomaly at $T_N=0.84$ K. The temperature dependence of the magnetic peak intensity corresponding to the ordered moment of Er$^{3+}$ approximates to the two-dimensional Ising universality class. Thermal- and cold-neutron inelastic scattering experiments demonstrate that the strong Ising anisotropy originates from the local crystal electric field, and reveal gapped magnetic excitations with weak dispersion in the ordered state. Mean-field random-phase approximation with inequivalent nearest-neighbor couplings accounts well for the collective excitations, while classical Monte Carlo simulations yield the fractional $1/4$ and $1/2$ magnetization plateaus. Our work provides a comprehensive description of the spin correlations in Er$_2$Be$_2$GeO$_7$ with a particular focus on the classical origin of its fractional magnetization plateaus.

Active materials are driven out of equilibrium at the microscopic scale and display diverse phenomenology; non-reciprocity is a subclass of activity in which action-reaction symmetry is also broken. These models are often grouped by the order of symmetry of their components, such as polar bird flocks or hexatic cellular tissues. However, many biological examples exist in which the components appear to have two or more symmetries simultaneously. To study this effect we introduce two independently controllable symmetries to the non-reciprocal XY model. This lattice model demonstrates wide ranging behavior dictated by the chosen symmetries. We derive a full hydrodynamic description of our lattice model that highlights the mechanisms driving its behavior. Each combination of symmetries can lead to a different hydrodynamic model with one or two simultaneous order parameters with different levels of orientational order that can appear active or not.

We introduce and analyze the $\delta$-Ising model, a kinetic Ising ferromagnet in which single-spin flips are accepted when their energy change does not exceed a tunable threshold. Varying the field and threshold opens or closes local flip channels, dividing parameter space into kinetic sectors, each governed by a fixed Markov transition operator. We prove that the dynamics retains global spin-inversion symmetry exactly when up and down spins have equal numbers of open channels. In one such sector on a periodic chain of length $L$, unbiased random initial states therefore reach the field-aligned and antifield states with probability $1/2$ each. Closing a single channel leaves both states absorbing but makes the probability of ordering against the field decay as $(2/\pi)^L$. Parameter sweeps correspond to ordered products of sector operators, which separate reaching a state from holding it, so hysteresis appears when a state is reached and released at different sector boundaries. We also show how increasing the system size can induce a Mpemba-like reversal, allowing a state with more misaligned spins to reach the final ordered state sooner on average. On a periodic chain, this reversal arises because the mean absorption time grows logarithmically with system size for many short domains but linearly for a single macroscopic domain, and it disappears when the bulk flip channel is opened. These findings show how a simple, intuitive rule for Ising dynamics links local kinetic constraints to field response, memory, and relaxation within a unified framework.

The nanobridge junctions (NBJs) allow the miniaturization of the Superconducting Quantum Interference Device (SQUID) and improve the spatial resolution of scanning SQUID microscopy. However, the SQUID loop diameter imposed a fundamental limit on the resolution. In this work, we proposed a single niobium-nitride-based three-dimensional nanobridge junction (NbN-3D-NBJ) alternative to the nanoSQUID for high-resolution magnetic imaging. The critical current of an NbN-3D-NBJ showed an nearly monotonic dependence on the external magnetic field, enabling nanoscale mapping of the magnetic field distribution by measuring the junction's critical current with an intrinsic noise level of 100 nT/Hz^1/2. Using a NbN-3D-NBJ probe, we successfully imaged an Abrikosov vortex in a niobium film with a minimal full width at half maxima (FWHM) of 530 nm, constrained by the distance from the junction to the probe tip edge. Furthermore, we resolved 80 nm spacings between the superconducting nanowires utilizing a second probe with an optimized junction-to-tip distance. Thus, the single 3D NbN NBJ probe has been demonstrated as an effective approach for magnetic imaging with ultra-high spatial resolution.

Transition-metal-based batteries rely on critical elements such as lithium, cobalt, and nickel. Their extraction creates environmental and supply-chain challenges. Organic electrode materials (OEMs) reduce this reliance and provide broad molecular tunability. However, OEM-based batteries still show limited long-term cycling stability. Their design also requires the joint optimization of coupled metrics such as voltage, specific capacity, capacity retention, and energy density. These metrics depend on the full battery stack and on the interactions among its components rather than on the active material alone. In our previous work, we developed a data-fusion multi-task framework for average discharge voltage and first-cycle specific capacity. Both targets are single-valued. Here, we extend that framework to multi-horizon prediction by predicting a property at every cycle of a discharge trajectory rather than at a single cycle. Our multi-fidelity and Multi-horizon Deep Operator Network learns DFT redox potentials and cycle-dependent specific-capacity trajectories within one model. We train it on complete battery-stack representations and usage conditions, so it learns battery-stack interactions rather than cathode-only effects. This framework supports long-term property prediction, inverse design, and process optimization for organic battery systems.

Understanding the fluctuations and response of particles in potential landscapes is a fundamental problem in nonequilibrium statistical physics. Here, we investigate how negative mobility reshapes the stochastic behavior of a particle moving in a mechanical potential landscape. We consider a one-dimensional overdamped particle subject to additive noise, with mobility that is negative at weak forces and positive at strong forces. In a potential well, negative mobility destabilizes the mechanical potential minimum and produces bimodal localization at two off-center positions. The same stability reversal transforms conventional Kramers escape from a potential well into a two-stage escape process involving an intermediate metastable state. When an additional spatially uniform force is applied, the mechanical perturbation translates rather than tilts the effective double well, yielding a positive response dominated at weak noise by intrawell relaxation, even though slow interwell switching dominates spontaneous positional fluctuations. These findings reveal how negative mobility reshapes the interplay among mechanical landscapes, stochastic stability, and response.

We theoretically analyze the spin-polarized tunneling between SmB$_6$ tip and the bicollinear antiferromagnet Fe$_{1+x}$Te. The emergence of magnetic contrast in tunneling requires time-reversal symmetry breaking on the surface of the tip. The magnetic contrast part of the tunneling conductance then has two contributions: the first one originates from the magnetic moment due to the equilibrium long-range order on the surface, while the other is governed by the magnetic moment induced by the electric field of the junction through the surface magneto-electric effect. We show that the ratio of the equilibrium moment to the response extracted near zero bias equals, up to the sign, twice the bias at which the contrast changes sign, independently of the relative strength of the two mechanisms, so that this ratio itself does not measure the strength of the magneto-electric effect. We find that within the experimental energy window $|eV|\lesssim10$~meV the {bias-dependent} field-induced contribution is at most a few percent of the equilibrium one, and the two become comparable only at biases of order $100$~meV or higher. The ratio of the field-induced to the equilibrium contribution is inversely proportional to the distance between the tip and the substrate.

Spintronic terahertz (THz) emitters based on ferromagnet/heavy-metal bilayers provide an efficient route for generating broadband THz radiation through ultrafast spin-to-charge conversion. However, Ni/Pt bilayers usually exhibit relatively weak THz emission, limiting their use as efficient spintronic emitters. Here, we report an interface-assisted enhancement of THz emission in ZnO/Ni/Pt heterostructures. By placing ZnO underneath Ni while preserving the direct Ni/Pt contact, the THz amplitude is increased by up to approximately 2.8 times compared with the Ni/Pt reference. The enhanced emission reverses polarity with the magnetic field and follows the expected angular dependence of ultrafast spin-to-charge conversion. ZnO-, Ni-, and Pt-thickness-dependent measurements show that the emission remains governed by the Ni/Pt conversion process but is strongly affected by the ZnO/Ni bottom interface. Control samples with Al2O3, Cu, and Fe further exclude a simple underlayer, optical, or growth-quality origin. The enhancement is attributed to a short-range ZnO/Ni interface effect, possibly involving oxygen-related defects, interfacial electric fields, and modification of the Ni interfacial state. This work provides a semiconductor/ferromagnet interface-engineering strategy for activating weak Ni/Pt spintronic THz emitters.

We show how the successful recent statistical physics based theory of overfitting in Generalized Linear Models (GLMs) can be generalized to a much larger family of regression models: the so-called Vector Generalized Linear Models (VGLMs), in which not a single linear combination of covariates drives the outcome, but where one has an arbitrary finite number of such linear combinations. The latter more general and complex models can describe more sophisticated statistical patterns in data, but are even more prone to overfitting than GLMs due to their significantly larger number of parameters; this often limits their use. We show that the generalization of the overfitting theory from GLMs to VGLMs causes many mathematical challenges that were absent from the earlier work, mostly related to the increased dimensional complexity of all order parameters in the theory, but that the new problem is once more solvable using the replica method. This opens up the field to many novel and welcome applications, especially in post-genome medical inference and data analysis, where overfitting is and remains a major barrier to progress. After developing the general VGLM overfitting theory, within the replica symmetric (RS) ansatz, we illustrate its merits and its correctness via application to several relevant VGLM regression models.

Angle-resolved photoemission spectroscopy (ARPES) was developed in the 1970s-1990s as a momentum-resolved probe of the electronic structure of solids, with its basic principles summarized in early seminal works and classic reviews. The basic ARPES result is currently almost exclusively associated with the two-dimensional intensity distribution with coordinate axes labeled as Binding Energy and Momentum. Such datasets are usually directly compared to the band structure calculations along high symmetry directions of the Brillouin zone. Here we show that this is the result of an oversimplified treatment of the ARPES data leading to incorrect interpretations of the experimental results. We suggest practical ways of how to avoid it in both data collection and analysis.

By means of diffusion Monte Carlo calculations, we study the behavior of a single impurity embedded in two balanced Fermi baths across the BCS-BEC crossover. The impurity interacts attractively with both baths through Pöschl-Teller potentials of different strengths. That interaction is such that does not support an impurity--bath two-body bound state. When that attraction is sufficiently strong, we observe the formation of trimers composed of the impurity and one atom from each bath. These clusters are Borromean on the BCS side, where no two-body subsystem is bound, and evolve continuously into tango-like trimers on the BEC side. Subtracting from the total energy the binding energy of one trimer and that of the remaining bath-bath dimers restores the equation of state of the impurity-free system, supporting a dilute-cluster interpretation. The analysis of interparticle distances shows that the embedded trimer is not simply a dimer dressed by the impurity, but a genuine three-body cluster formed inside the two Fermi baths.

Bi2Sr2CaCu2O8+x (Bi-2212) is a d-wave superconductor with unconventional properties intrinsic to the material itself. These properties are of growing interest for quantum technologies in electronics and photonics, and twisted Josephson junctions can make direct use of them. However, Bi-2212 is strongly anisotropic, and it is challenging to find its crystal axes in flakes in advance, which limits device engineering. Here, we show that polarized resonant Raman spectroscopy reveals the orientation of both the a and b axes of Bi-2212 optically and non-destructively. By correlating Laue diffraction, HAADF-STEM and polarized Raman scattering on the same bulk crystal, we assign the b axis, along which the incommensurate structural supermodulation propagates, to the intensity maximum of the 27 cm-1 supermodulation mode, which varies in counter-phase with the 118 cm-1 Bi/Sr mode, along the a axis. Multi-wavelength measurements (458, 532, 660 nm) show that resulting in-plane contrast peaks at 532 nm and nearly vanishes at 660 nm, indicating that the anisotropy originates from an electronic resonance induced by the supermodulation. Using this resonance, we determine the crystallographic axes of exfoliated flakes and access their symmetry channels, providing a rapid orientation tool for cuprate van der Waals heterostructures.

In non-centrosymmetric bulk materials, electrons flowing in the opposite directions often exhibit different properties. This diode-like effect (i.e., non-reciprocal electron transport) typically originates from relativistic spin-orbit coupling, and its amplitude scales with external magnetic field or magnetization in ferromagnets. Although such rectification is usually absent in antiferromagnets at zero field, recent theories predict that non-coplanar antiferromagnetic order can host large non-reciprocity even without spin-orbit coupling, magnetization or external magnetic fields. This phenomenon - the spontaneous topological diode effect - can potentially be used for efficient electrical readout of antiferromagnetic domains, while it has not been verified for real materials. Here, we report the observation of this effect in a chiral-lattice non-coplanar antiferromagnet CoTa3S6. Nonlinear resistivity measurements reveal the non reciprocal nature of electron transport along the [001] direction at zero field. The observed non-reciprocity exceeds that in typical ferromagnets, whose amplitude is governed by antiferromagnetic order parameter rather than magnetization. First-principles calculations show that the non-coplanar antiferromagnetic order induces asymmetric band dispersions even without spin-orbit coupling, establishing the non-relativistic origin of the observed response. The present findings demonstrate a new mechanism for efficient electrical readout of antiferromagnetic domains, and highlight non-coplanar antiferromagnets as a promising material platform for realizing ferromagnet-like functional responses without relying on spin-orbit coupling or magnetization.

Magnetic skyrmions in synthetic antiferromagnets have emerged as attractive information carriers for spintronic technologies due to their compensated topology, which mitigates the skyrmion Hall effect and facilitates reliable current-driven transport. Here we present a frequency-tunable magnetic clocking concept based on the recurring translational motion of SAF skyrmions and define the material conditions needed to realize it in a Pt/Co/Ru/Pt/Co multilayer. Using micromagnetic simulations, we investigate the combined effects of interfacial Dzyaloshinskii-Moriya interaction and interlayer Ruderman-Kittel-Kasuya-Yosida exchange coupling, delineating the parameter space in which coupled Néel-type skyrmions with opposite topological charges form a stable, topologically compensated pair. Under spin-orbit torque excitation, the SAF skyrmions exhibit resilient longitudinal transport with minimal transverse deflection using periodic boundary conditions. Periodic boundary conditions serve as an idealized model for closed-loop racetrack geometries, facilitating the study of continuous transport cycles and long-range steady-state dynamics. The oscillation frequency is readily modified by the applied current density and material characteristics, offering a pathway to field-free nanoscale timing components. Moreover, the threshold-activated initiation of recurrent transport mimics tonic-spiking behavior, indicating possible use in neuromorphic signal generation. This work establishes SAF skyrmions as versatile building elements for future spintronic functional devices by integrating topological protection, controllable transport, and cyclic dynamics.

Mechanical stress is one of the main characteristics of viscoelastic molecular systems, including vitrifying liquids and amorphous solids which are known to show long-range dynamical heterogeneities. It is therefore important to deal with time- and space-resolved local stress whose correlations can be used to obtain viscoelastic memory functions of such systems, in particular, their wave-vector dependent shear and compression relaxation moduli. However, such memory functions are not directly accessible within standard molecular dynamics (MD) simulations. Here we discuss a new method called the constrained molecular dynamics (CMD) which allows for a direct evaluation of the wave-vector and time dependent viscoelastic moduli. The study is focused, in particular, on the stability analysis of different variants of the CMD, revealing the most efficient stabilization algorithm. Our theoretical predictions for the time-dependence of the most important parameters (like the wave-vector resolved mass current) during the stabilization stage are compared with the simulation data using different CMD algorithms. An excellent agreement is observed, thus confirming the validity of our theoretical approach and its ability to accurately predict the most important initial part of CMD trajectories.

This study examines how deposition potential influences the composition and nanoscale structure of Prussian Blue (PB)/Prussian White (PW)-family films, providing an experimental basis for assessing their proposed functions. Films were grown directly on Au/Cr/Si in a single potentiostatic step from a common aqueous bath at $-0.20$ to $+0.40$\,V versus a saturated calomel electrode, with a fixed deposition charge of 10\,mC. Electron microscopy, elemental analysis, X-ray photoelectron spectroscopy, and Raman spectroscopy revealed potential-dependent chemistry and nonmonotonic morphology. EDS indicated greater K incorporation in lower-potential deposits, whose Fe~2p and Raman features were consistent with more reduced, PW-like environments. Surface K/Fe ratios varied nonmonotonically from 1.129 to 1.322 across the series, corresponding to 52.95--56.94\% K within the detected K+Fe population. Larger faceted crystallites at $+0.30$\,V contrasted with finer pyramids and cracks at $+0.40$\,V. Selected PB-like and PW-like regions had local cubic lattice parameters of $(10.31\pm0.10)$\,Å and $(10.36\pm0.10)$\,Å, respectively; their overlapping uncertainties prevent discrimination by lattice spacing alone. Cross-sectional maps showed broadly uniform framework-element distributions within locally continuous coatings. Together, these observations relate deposition conditions to contrasting chemical and morphological starting states without establishing bulk stoichiometry or phase purity. A literature-grounded outlook identifies ion storage, sensing, electrochromism, resistive switching, and ion handling as research opportunities requiring functional validation in these films.

Interactions shape the properties of many physical and biological nonequilibrium systems, but whether collective operation raises or lowers entropy production remains difficult to predict. Here, we show that strong coupling suppresses irreversible circulation associated with the directly coupled degrees of freedom. In identical two-dimensional systems, this suppression is monotonic for nonzero coupling modes and guarantees a monotonic decrease of the entropy production rate (EPR), with the corresponding probability currents vanishing in the strong-coupling limit. In higher dimensions, suppressing the circulation associated with the coupled degrees of freedom does not generally eliminate all irreversible circulation, since the remaining degrees of freedom can still sustain nonequilibrium currents. The EPR of these residual dynamics sets the strong-coupling limit, providing a criterion for whether a given choice of coupled variables leads to lower dissipation than the uncoupled system. The approach to this limit depends on how the finite-coupling current correction aligns with the residual current. Further, we show that convergence to residual dynamics in the strong-coupling limit also applies to coupled non-identical systems. Finally, we demonstrate the predicted EPR reduction in nonlinear models of vertebrate hair-cell bundles and bacterial chemotaxis.

The spinterface model of chirality-induced spin selectivity supports two algebraically distinct near-exceptional-point (EP) regimes, which cannot be mixed. A \emph{gold-level} near-EP involves the two gold spin states under an anti-Hermitian, electrode-mediated spin flip with spin-symmetric dissipative broadening (Scheme~B). A \emph{chain-level} near-EP involves the collective coalescence of the two molecular eigenstates with largest weight on the first molecular site under a Hermitian on-site Rashba spin flip with spin-dependent broadening (Scheme~A). Mixing the diagonal cancellation of one scheme with the off-diagonal structure of the other yields a strictly negative discriminant and admits no EP on any parameter path, making the gold/chain classification exhaustive. At the gold near-EP the spin-flip coupling is chirality-selective, converting achiral spin-valve transport into purely chiral transport across well-defined crossover points. At the chain near-EP the Petermann factor grows as a power law in chain length, with an exponent tunable by the Rashba coherence length and non-monotonic in the Rashba strength, reflecting a balance between coherent enhancement and progressive breakdown of the Scheme-A condition. Both near-EPs are dressed versions of the ideal two-state EP, and the ratio between observed and bare EP locations measures the delocalisation of the coalescing pair, providing a fit-free diagnostic of the mechanism. These results identify CISS junctions as a solid-state platform for non-Hermitian spectral physics.

The structural accessibility and perimeter shell properties of branched macromolecules are studied using Monte Carlo simulations on a simple cubic lattice. Constituent polymer chains of these macromolecules are constructed in an algorithmic way as: a set of collinear monomers; a self-avoiding walk (SAW); tigthly packed monomers. These mimic the ground states for a rigid rod, flexible chain, and collapsed chain conformational states, respectively. We analyzed the set of observables that are related to adsorption, such as perimeter shell size (number of available sites for particle adsorption) per monomer $\langle \bar{n}_a \rangle$, mean coordination number of perimeter shell $\langle n_{\rm bond} \rangle$ (average number of contacts per adsorbed particle), and coordination accessibility per monomer $\langle \bar{n}_s \rangle$. Our results demonstrate that branching reduces the perimeter shell size while it increases mean coordination number of perimeter shell across all conformational states, due to higher local monomer density near branching cores and formation of shared adsorption sites or microcages. Stiff extended structures yield the highest values for $\langle \bar{n}_a \rangle$ (approaching $4$ in the limit of long chains), whereas the flexible ones provide the largest values for $\langle n_{\rm bond} \rangle$. We can note that the collinearity of monomers in constituent chains works in the same direction as reduction of branching ($\langle \bar{n}_a \rangle$ grows), whereas the { tight packing of them} -- in the same direction as the increase of branching ($\langle \bar{n}_a \rangle$ decreases)

We study statistics of transport properties in a system of two quantum chaotic cavities coupled in series through a tunable junction and connected to reservoirs with asymmetric leads. Within the random matrix theory framework and in the absence of time-reversal symmetry, the scattering matrix S undergoes a crossover from two independent circular unitary ensembles to a single CUE as the inter-cavity coupling increases. Modeling this crossover using Dyson's Brownian motion approach, with the junction width acting as a time-like parameter, we derive closed-form expressions for the time-dependent averages and variances of conductance and shot noise power for arbitrary lead asymmetry. These analytical results reduce to known expressions in the symmetric and fully coupled limits. The mapping between the Brownian time parameter and the physical junction width is found to be observable-dependent, reflecting the different eigenfunction correlations probed by conductance and shot noise power, and this dependence is examined and separately calibrated for each observable. Validating against random-matrix simulations and tight-binding transport calculations using Kwant, we find quantitative agreement for ensemble-averaged observables throughout the crossover, while variances, being more sensitive to microscopic fluctuations, show deviations from the Brownian-motion predictions.

Opening a band gap in metallic two-dimensional carbon allotropes is an important step toward their use in electronic and optoelectronic devices, and full hydrogenation has proven to be an effective route to achieve it. Here, we propose irida-graphane, the fully hydrogenated derivative of the irida-graphene, a monolayer composed of three-, six-, and eight-membered rings, and investigate its structural, mechanical, electronic, and optical properties using density functional theory (DFT) at the PBE and HSE06 levels combined with phonon and \textit{ab initio} molecular dynamics (AIMD) simulations. All carbon atoms adopt $sp^3$ hybridization, with the hydrogen atoms of the three- and six-membered rings bonded to opposite sides of a buckled carbon framework, and the lattice parameter contracts by 4.3% with respect to irida-graphene. The hydrogenation energy of $-0.53$ eV/H indicates that the hydrogenation of irida-graphene from molecular hydrogen is exothermic. The absence of imaginary phonon frequencies confirms the dynamical stability of irida-graphane, and AIMD simulations show that its structure remains intact at temperatures up to 2000 K. Irida-graphane is mechanically isotropic, with an in-plane stiffness of approximately 156 N/m, a Poisson's ratio of approximately 0.1, and critical strains of approximately 20%. Hydrogenation transforms the metallic parent structure into a semiconductor with an indirect band gap of 4.68 eV (PBE) and 6.0 eV (HSE06). Irida-graphane is transparent in the visible range, with reflectivity below 0.3%, and absorbs strongly in the deep ultraviolet, with absorption coefficients of the order of $10^{5} - 10^{6}$ cm$^{-1}$. These results suggest irida-graphane as a candidate wide-gap material for ultraviolet optoelectronics and transparent coatings.

In recent years, statistical physics tools have been used to study the dynamics of macroscopic quantum and classical integrable models. These studies have shown that, in the thermodynamic limit, long term time-averages of local observables equal statistical averages calculated with a Generalized Gibbs Ensemble (GGE). In the latter, the weight in phase space involves all constants of motion multiplied by Lagrange multipliers which are fixed by their initial values. We argue that the GGE can be interpreted as a proper Boltzmann measure of a different (non-standard) mechanical model. This measure can therefore be sampled with stochastic methods implemented, for example, as a Langevin process. We tailor the deterministic force in the Langevin equations so that at long times the stochastic trajectories sample the desired measure. We use the integrable Neumann Model -- the model of a classical particle constrained to move on a sphere under anisotropic harmonic potentials -- as a benchmark. We test the method in a setup where the Lagrange multipliers are fixed by the GGE governing the asymptotic dynamics of the isolated Neumann model following a quench. This problem has different phases depending on the initial conditions and quench protocol and, in all cases, with the stochastic evolution of an adequately tuned Langevin process we reproduce the asymptotic values of relevant observables.

Vertically-aligned MoS$_2$ films paired with a Cu top electrode have been used as electrochemical metallization cell memristor devices. The memristive switching has been attributed to the formation of conductive filaments, yet their exact structure has remained elusive. Here we carry out a multi-scale computational study of Cu intercalation, clustering, and field-driven dynamics to eventually model the filament formation under operating conditions. We use density-functional theory results to fine-tune a machine learning force field, and the most important physical phenomena are further distilled into multi-particle kinetic Monte Carlo simulations. By exhaustive enumeration of Cu intercalated structures, we find the most stable structure at MoS$_2$Cu$_{0.11}$ composition, with Cu atoms forming a dice lattice between the MoS$_2$ layers. These structures are shown to exhibit metallic character and can thus form conductive filaments under memristor operation. The simulated switching speed and threshold voltage agree well with the available experimental data. Our results give fundamental insights on the device operation mechanism and guidelines for maximizing switching speed and endurance.

Boundary dissipation can reshape the spatial profiles and decay properties of topological edge modes in Chern insulators. We develop a microscopic boundary-channel framework to explain their decay mechanisms and determine the effective decay rates in the weak- and strong-loss regimes. By retaining the lossy outer orbitals and a normalized edge state of the Hermitian inner system, we identify a directly coupled bright boundary channel, while incorporating the remaining inner states through a Feshbach self-energy. In the Qi--Wu--Zhang model, weak-loss decay is governed to leading order by the original edge state's probability weight on the lossy boundary, with coupling-induced corrections starting at cubic order. At strong loss, the reconstructed inner-edge state instead decays through virtual coupling to the damped bright channel, giving a rate proportional to the squared microscopic coupling and inversely proportional to the bare loss. The Haldane model shows that the same leading decay mechanism holds for a different intercell hopping structure, while additional matrix-valued self-energy feedback modifies the boundary spectrum at finite loss and shifts the exceptional-point threshold. These results provide a unified microscopic description of boundary-state reconstruction and its decay mechanisms, offering testable predictions to guide experiments in photonic crystals, phononic crystals, and topolectrical circuits.

We carried out molecular dynamics simulations of a mixture of self-propelled particles (SPPs) and passive particles. When the self-propulsion speed was sufficiently high, the system separated into two phases. One phase consists of ordered passive particles, and the other is a disordered mixture of both particle types. The separation arises from the interplay between the self-propelled motion of SPPs and thermal motion of the passive particles, since phase separation does not appear with either particle type alone. As the self-propulsion speed increases, the SPPs push surrounding particles away, effectively increasing their excluded size. As a result, the increase in the effective excluded sizes promotes the accumulation of passive particles and the segregation of SPPs into the dilute phase through a mechanism analogous to the depletion interaction. This mechanism explains the phase separation observed in the present study. Our findings provide insights into the potential applications of SPPs and contribute to our understanding of natural systems composed of elements with different levels of motility.

We introduce GMMag, a workflow for generating crystal structures together with their site-resolved magnetic moments, built on a conditional variational autoencoder with a graph neural network encoder and a transformer decoder. Gaussian-mixture sampling redirects generation towards selected chemical and magnetic targets without retraining. We systematically investigate how encoder and decoder design, the representation of magnetic-moment magnitudes and relative signs, and sampling choices affect reconstruction, generation quality and diversity. Because a higher screening pass rate does not necessarily yield more qualifying candidates with distinct chemical formulas absent from the reference dataset, we model how repeated generation of the same chemical formulas limits their accumulation and test the model in two separate ten-million-draw runs. As an application, the workflow identifies Nd-containing candidates with chemical formulas absent from the reference dataset, negative formation energies and high estimated saturation magnetization.

Magnetic textures offer a route toward photonic functionality in which electromagnetic fields are controlled not only by material composition and geometry but also by the internal magnetic configuration. Conversely, spatial texturing of these fields is a qualitatively new tool to increase the effective coupling strength to magnetic matter and to act on the the vortex topology and magnetic dynamics. Here, we investigate the coupling and scattering of structured electromagnetic fields by a magnetic vortex, focusing on how spatially non-collinear magnetization governs polarization conversion, electromagnetic energy flow, and magnetization dynamics. We develop a spherical rigorous coupled-wave method that incorporates the spatially dependent anisotropic magnetic permeability associated with the vortex texture. The calculations show that the off-diagonal components of the magnetic susceptibility mediate conversion into complementary polarization channels that are absent from the incident field. The generated fields exhibit pronounced spatial localization associated with the vortex magnetization profile and support a nonzero azimuthal component of electromagnetic energy flow. A comparison between linearly and radially polarized illumination reveals an approximately one-order-of-magnitude difference in the scattered fields amplitudes due to polarization texturing, demonstrating the importance of spatial overlap between the incident field and the anisotropic magnetic response. The back-action on the magnetic vortex dynamics is quantitatively demonstrated by numerical simulations for the inverse Faraday effect due to the rectification of structured effective-field excitation. It is shown that polarization textured optical fields can drive vortex-core precession and, at sufficiently strong excitation, reverse the core polarity and chirality on nanosecond time scale.

Within the framework of the classical Monte Carlo method with kinematic account of constant bosons concentration a model nickelate was studied, its magnetic structures for various values of exchange integrals considering up to third-nearest neighbours were determined.

We study perfect sampling algorithms for Ising spin glasses based on coupling from the past and bounding chains, on several graph families and coupling distributions. For the single-site bounding chain, we establish coalescence in $O(n\log n)$ updates under Dobrushin conditions. On sparse random graphs, our numerical results suggest that efficient sampling extends throughout the tree-uniqueness regime, with a slowdown beyond this threshold. On Erdős-Rényi random graphs $\mathcal{G}(n,d/n)$ with standard Gaussian couplings, we introduce a block bounding chain and prove its coalescence in $O(n\log n)$ block updates in the tree-uniqueness regime for sufficiently large $d$, each block update requiring $O(n)$ operations, adapting a proof in~\cite{Efthymiou_Zampetakis_2024} for the rapid mixing of block Glauber dynamics. On periodic lattices, our experiments instead suggest that the single-site bounding chain is limited by the looseness of its bounding envelope, whereas on the Sherrington-Kirkpatrick model, slow coalescence is accompanied by damage spreading at every inverse temperature tested. These observations motivate alternative bounding representations and couplings as strategies to improve perfect sampling on spin glasses.

We develop the theory of hydrodynamic fluctuations for one-dimensional quantum liquids. At low temperatures the relaxation of interacting electrons in a single-channel wire separates into two classes: equilibration, which changes the numbers of right and left movers through backscattering and is exponentially slow, and thermalization, which redistributes energy and momentum at a fixed number of movers at a power-law rate. This separation of time scales gives the electron liquid a two-fluid description analogous to superfluid $^4$He, with the zero mode of the Luttinger liquid as the superfluid component and the gas of thermal excitations as the normal component. Using Onsager reciprocity and the fluctuation-dissipation theorem, we add Langevin fluxes to the two-fluid hydrodynamic equations, including a mutual-friction noise generated by rare backscattering events that has no counterpart in helium. We apply the theory to Coulomb-coupled quantum wires and calculate the dynamic structure factors, which contain a second-sound peak next to the plasmon doublet; the Coulomb drag resistivity, where intrawire equilibration acts as a bottleneck and turns the hydrodynamic drag into an activated temperature dependence; and the near-field heat transfer between the wires. Mode frequencies, spectral weights, linewidths, and the crossover scales of the transport coefficients are expressed through the thermodynamic properties of the liquid and a few dissipative coefficients, providing spectroscopic and transport probes of two-fluid behavior in one-dimensional quantum systems.

The superconducting state of $2H-NbS{{e}_{2}}$ was studied using point contacts for two main orientations of the contact axis relative to the principal crystallographic orientations: along the $c$-axis and in the $ab$ plane. For contacts oriented in the $ab$ plane, dependencies proportional to the electron-phonon interaction function were obtained, which agree perfectly with the theoretical calculation. It was found that the features on the experimental curves associated with the electron-phonon interaction extend to energies twice the cutoff energy of the phonon spectrum and have an amplitude of the same order of magnitude throughout the entire energy range. It has been theoretically demonstrated that the features at energies exceeding the boundaries of the phonon density of states are caused by two-phonon scattering processes of non-equilibrium phonons on Andreev electrons. A criterion for the undisturbed nature of the crystal lattice in the region where gap features form has been found. Using $2H-NbS{{e}_{2}}-Cu$ heterocontacts in the superconducting state, a study of energy gaps was conducted for two orientations of the $NbS{e_2}$ crystal: along the $c$-axis and in the $ab$ plane. It was found that the superconducting energy gaps are anisotropic; specifically, three gaps were identified in the $ab$ plane, whereas only two were observed in the $c$ direction.

Classical Coulomb crystals and quantum Wigner crystals typically arise when repulsive interactions order like-charged particles in spatially confined environments. Here, we show that transient crystallization can also emerge in freely propagating electron pulses without external trapping. Experimentally, we use a transmission electron microscope to measure number-resolved energy correlations in photoemitted pulses containing up to nine electrons, revealing strong correlations at small particle numbers that progressively disappear in the pulse interior as the number increases. To explain these observations, we combine many-body simulations with a one-dimensional statistical-mechanical model, showing that the leading and trailing electrons generate a self-induced longitudinal potential that transiently confines the inner particles, enabling the formation of an ordered chain during propagation. The resulting crystallization phase diagram reveals how many-body ordering dynamics can be understood in terms of evolving macroscopic beam properties, namely its geometry and the ratio of the mean Coulomb interaction energy to the longitudinal thermal energy. Extending this framework, we theoretically demonstrate that weak transverse guiding through electrostatic or optical ponderomotive forces can sustain crystallization at larger particle numbers and predict spontaneous longitudinal periodic bunching in continuous electron beams. Our results identify conditions under which stochastic Coulomb interactions can be harnessed to generate self-structured, strongly correlated electron beams in both pulsed and continuous regimes.

LaNiGa2 has attracted considerable interest as a candidate unconventional superconductor, particularly due to its reported time-reversal symmetry breaking and nonsymmorphic crystal structure hosting symmetry-protected electronic band degeneracies. Here, we report the growth and characterization of superconducting LaNiGa2 thin films on MgO substrates by magnetron sputtering. X-ray diffraction reveals highly crystalline, (010)-oriented films with well-defined in-plane alignment and rotational twinning. Electrical transport measurements establish superconductivity with a transition temperature of approximately 1 K. Atomic-resolution transmission electron microscopy reveals local variations in crystallographic orientation and interlayer stacking, with a predominantly Cmcm structure containing minority Cmmm regions. The coexistence of these closely related structures reveals local stacking polymorphism that is difficult to distinguish using conventional X-ray diffraction. These findings establish a superconducting LaNiGa2 thin-film platform and provide new insight into the local crystal structure of a material whose electronic properties and superconducting pairing remain under active investigation.

Conventional altermagnetic spin splitting arises from staggered exchange and sublattice-dependent anisotropic hopping without requiring spin-orbit coupling (SOC). Here we derive a low-energy effective model showing that SOC and staggered exchange can jointly activate additional spin splitting on momentum planes where the nonrelativistic contribution vanishes. In hexagonal $\alpha$-MnTe, this SOC-activated contribution produces d-wave spin splitting near $\Gamma$ with out-of-plane spin polarization. Its leading angular pattern counter-rotates by half the in-plane Néel-vector rotation angle. First-principles spin-transport calculations reveal a corresponding approximate half-angle locking between the Néel-vector orientation and the electric-field directions maximizing the signed longitudinal and transverse spin conductivities. Analytical transport calculations based on the effective model trace this locking to the same angular coupling between momentum and the Néel vector that governs the spin-splitting pattern. Our findings connect the microscopic mechanism of SOC-activated altermagnetic spin splitting to directional spin transport, providing a theoretical basis for probing Néel-vector orientation and controlling spin-current generation.

Application of a finite electric field and small twist angle between two graphene bilayers leads to widely tunable electronic structures that support emergent phenomena. Here, we measure the electronic structure of twisted double bilayer graphene with twist angles of 3.1$^{\circ}$ and 6.0$^{\circ}$ using micro-focused angle-resolved photoemission spectroscopy (microARPES) on \textit{in situ} gated samples. At a twist angle of 6.0$^{\circ}$, we find that the dispersion around the valence and conduction band extrema is unchanged compared to separate graphene bilayers, whereas electric field tunable hybridisation gaps and band flattening effects occur at higher binding energies. In the 3.1$^{\circ}$ structure, we find that the resulting superlattice drives dispersion changes around the valence and conduction band edges. Increasing the gate-induced doping in the bottom bilayer leads to the formation of flat bands between the valence band maximum in the bottom bilayer and conduction band minimum in the top bilayer. Our experiments establish combinations of twist angle and electric field that potentially support strong electron-hole excitations and that provide a benchmark for the theoretical description of moderately twisted double bilayer graphene.

The chaos picture is a novel, coherent, and intuitive theoretical framework for spin glasses, reconciling the 40-year-old droplet vs. replica symmetry breaking debate. First, we argue the formation of a hierarchical energy landscape by pinning and dynamic filtering of random droplets. As the temperature decreases, the chaos picture describes a progressive freezing of scale-dependent droplets in real space, which mirrors a hierarchical free energy landscape fracturing process in phase space. This bifurcation process is accompanied by temperature chaos, leading to dynamic pure state coexistence without violating the droplet scaling. Crucially, the interface geometry is not critical to these mechanisms, naturally incorporating the interface crossover from planar, fractal, to space-filling as the dimensionality increases, in line with the mean-field limit. Finally, the chaos picture provides profound insights into spin-glass dynamics such as aging, rejuvenation, and memory effect, while offering a streamlined reinterpretation of the complex metastate framework.

The dielectric constant of polar liquids depends not only on the magnitude of the molecular dipole moment but also on short range orientational correlations between neighboring dipoles. How molecular structure determines these correlations, quantified by the Kirkwood correlation factor $g_\mathrm{K}$, remains unclear. Using molecular dynamics simulations of model polar liquids without hydrogen bonding, we show that molecular shape plays a central role. We interpret $g_\mathrm{K}$ as resulting from the combination of dipolar interactions and steric effects, which together favor either alignment or antialignment of neighboring molecules. Depending on molecular shape, $g_\mathrm{K}$ can either increases or decreases upon cooling, or change monotony. A minimal model of dipoles on a cubic lattice reproduces these three regimes and attributes the nonmonotonic case to a competition between the first layer of neighbors, which favors alignment, and the second layer, which favors antialignment.

This thesis develops diagrammatic methods for thermodynamic and subsystem quantities of interacting lattice fermions, providing reference calculations for quantum simulators and many-body approximations. I formulate an inverse-flavour expansion about a self-consistent Hartree saddle, enumerate non-Gaussian diagrams, and use a discrete Lehmann representation to integrate selected internal vertices analytically. Density results cover 31 state points of the six-flavour Hubbard model on a $70\times70$ lattice at $T/t=0.15$. I generalize combinatorial summation to flavour-dependent propagators and expansion shifts. CoS++ combines partial contractions to obtain connected sums for interaction subsets. A determinant-polynomial sieve evaluates the same sums through local coefficient filters; at ninth order it is 24--25 times faster than the specified CoS baselines in three-flavour dense-random-matrix benchmarks. Thermodynamic applications include a 2048-site honeycomb lattice and a three-flavour square lattice with 1024 sites. For the second Renyi entropy, I derive a fermionic replica path integral and a stable evaluation of its two-time Green functions. The connected-determinant calculation reaches tenth order on a $3\times3$ cluster and ninth order on larger lattices. On $50\times50$ sites at $(U/t,\mu/t,\beta t)=(3,1,8)$, the ninth-order continuation at shift $\alpha=1.3$ gives $S_2/N_s=0.06695$ with propagated Monte Carlo uncertainty $3.0\times10^{-5}$. Comparing two expansion shifts at their respective retained orders gives an endpoint difference of $2.6\times10^{-4}$.

Functionalising the back-end-of-line (BEOL) of CMOS with emerging materials is a key route to neural network accelerators and neuromorphic systems. In this work, we demonstrate for the first time the integration of 2-terminal ferroelectric synaptic weights in the BEOL of as-delivered commercial 180 nm CMOS dies. A novel material stack is proposed, in which a WOx/[HfO2-ZrO2] bilayer is sandwiched between TiN and Mo electrodes. For devices annealed at 450 °C, programming below 1.8 V is achieved with a cycle-to-cycle variation below 3 %. Synaptic weights annealed at 500 °C exhibit more gradual weight updates, while the tested underlying NMOS transistors remain functional after the complete integration process. The trade-off between thermal budget and on-device training performance is illustrated using hardware-aware neural network simulations.

Using an activation model reproducing facilitation mechanisms, we found recently a fluidization transition in supercooled water triggered by the motion of a few active molecules. We investigate here the effect of the activation force on the transition. The activation force increases the probability for active molecules to overcome the energy barrier induced by caging. The induced molecular motions result in an intermittent loose structure leading to a decrease of energy barriers around the moving molecule, thus facilitating the motion of nearby molecules. Therefore we expect the force, if small enough, to increase the facilitation mechanism, and as a result cooperative motions induced by it. As a result the activation force permits to tune facilitation and cooperative motions in active glass-formers. We find an optimum force for cooperative motions that we evaluate to be around 3.5pN, a value in the range of protein motor forces. As expected for a phase transition we observe peaks of cooperative motions (dynamic heterogeneity) on the transition. This result shows that dynamical heterogeneity are the cooperative motions of physical importance for the transition.

We construct a minimal field theory for critical quantum active matter, describing a nonconserved scalar order parameter with Landau-Ginzburg ordering and self-advection. When diffusive noise dominates, higher-order quantum vertices and non-Gaussian noise fluctuations remain relevant alongside the deterministic nonlinearities, with an upper critical dimension $d_c=2$. A one-loop renormalization-group analysis in $d=2-\epsilon$ reveals a purely dissipative fixed point, where nonlinear noise suppresses convection, and a quantum convective saddle, where interactions, convection, and non-Gaussian noise coexist. We determine the critical exponents, show that the convective regime is distinct from conventional Burgers hydrodynamics, and discuss how it could govern transient universal scaling in microscopic models of quantum active matter before a crossover to semi-classical dynamics.

A transition between an integer quantum Hall insulator and a chiral spin liquid can become critical without closing the single-electron gap, raising the question of which composite excitations govern the change in topological order. We investigate this question in the $\mathrm{SU}(3)$ triangular-lattice Hofstadter--Hubbard model at one particle per site and magnetic flux $\pi/3$ per triangle. Using infinite density matrix renormalization group calculations, we identify a weak-coupling integer quantum Hall phase and an interaction-driven $\mathrm{SU}(3)_1$ chiral spin liquid. Near the transition, both the neutral and charge-$3e$ correlation lengths increase substantially, whereas the single-electron correlation length remains short, providing evidence for a Chern--Simons--Higgs critical theory, where a gauge-invariant monopole carries the quantum numbers of a fermionic $\mathrm{SU}(3)$-singlet trion. We discuss the implications for doping the system and recent experiments on doping $\nu=-2/3$ fractional quantum anomalous Hall in tMoTe$_2$.

Much of the water that matters most - flowing through biological cells and membranes, percolating through soils and rocks, or processed by filtration and desalination technologies - is not bulk water. It is water in nano- and molecular-scale confinement or at interfaces. Nanoscale water is therefore central to many challenges of our time, from the global water crisis and the water-energy nexus to catalysis, electrochemistry, and health. Beyond its applications, nanoscale water has emerged as a rich scientific field in its own right: discoveries are accumulating rapidly, revealing that confinement and interfacial forces produce a range of behaviours absent in the bulk. Sometimes this amounts to a renormalization of bulk properties; in other cases, new and non-intuitive phenomena emerge - exotic phases, anomalous transport, and dielectric responses that defy continuum expectations. A convergence of atomically precise nanofluidic devices, novel spectroscopies and microscopy approaches, and machine-learning-accelerated simulations is now exposing the molecular mechanisms behind these behaviours. This Perspective argues that the recent findings should not be viewed as isolated nanoscale anomalies, but as evidence for a molecular regime of water in which continuum descriptions must be rethought and molecular-level understanding becomes essential. Recognising and exploring this regime should have consequences ranging from fundamental physics to the rational design of future technologies that rely on water and dissolved ions.

We present a native implementation of the Two/Three-Phase Thermodynamics (xPT, $x \in \{2,3\}$) method within the LAMMPS molecular dynamics framework, termed FixXPT. xPT is an approach for obtaining absolute, quantum-corrected thermodynamics (entropy, enthalpy, free energy, heat capacity, diffusivity) from the density of states function, obtained from the velocity autocorrelation function of an equilibrium trajectory. FixXPT addresses non-trivial integration challenges, including atom reordering, compute scheduling, FFT backends, unit systems, and partitioning of atomic velocities into molecular modes. Two autocorrelators are provided: a Wiener-Khinchin FFT correlator with one cumulative window-end operation, and an in-line multi-tau correlator whose memory footprint grows only logarithmically with the window length, removing the principal scaling bottleneck for long analysis windows. The velocity history of each window is distributed across the MPI ranks, so the memory the fix adds to a node stays nearly constant as ranks are added and its cost falls with the number of GPUs. Replaying identical velocity frames through FixXPT and the stand-alone pyxPT post-processor reproduces every thermodynamic observable of well-sampled groups to within 0.1 to 0.5% across the full analysis-mode matrix; sparsely populated ionic species agree within their statistical uncertainty, and the multi-tau VACF converges monotonically to the FFT result as its buffer grows, from 0.8% to 0.1% drift across a 16-fold buffer sweep. The code is distributed as a drop-in LAMMPS package.

Polymorphism in molecular crystals presents a major challenge for controlling crystallization. Here, we combine experiment and theory to characterize the polymorph landscape of acridine and investigate its selective control by additives. Melt crystallization experiments resolve the previously unknown structure of form VIII, while topological crystal structure prediction recovers all seven known unsolvated polymorphs with determined crystal structures. Combining a fine-tuned machine-learned interatomic potential with anharmonic free energy calculations reproduces the experimentally observed stability relationships and reveals a shallow free energy landscape. Finally, experimentally observed additive-induced polymorph preferences correlate with mixed-crystal substitutional defect energies and topological similarities between additive and acridine crystal structures. Together, these results provide a comprehensive picture of acridine polymorphism, linking crystal structure, thermodynamic stability, and additive-controlled crystallization.

Mediated interactions between quasiparticles lie at the heart of Landau Fermi-liquid theory, yet their behavior in the strongly correlated regime is not fully understood. Motivated by recent experiments [Nat. Phys. 20, 68--73 (2024)], we investigate mediated interactions between quasiparticles emerging from a Fermi sea---Fermi polarons---using zero-temperature quantum Monte Carlo methods. Our main result is that the Landau interaction between polarons remains repulsive in the strongly interacting regime for any coupling strength in the polaronic branch, in contrast to the downward trend observed experimentally near resonance. Deep in the short-range universal regime, our results are insensitive to the microscopic details of the interaction potential, providing robust evidence for the sign of the ground-state induced interaction. In addition, we determine the real-space interaction between static impurities, recovering a Ruderman-Kittel-Kasuya-Yosida (RKKY)-like behavior at weak coupling and the nonperturbative Born-Oppenheimer result at strong coupling. More broadly, our results establish a microscopic benchmark for how Landau quasiparticle interactions survive beyond the perturbative regime of strongly correlated quantum matter.

This paper focuses on the numerical and analytical determination of the mechanical parameters of aluminum-matrix nanocomposites using atomistic-scale simulations within a multiscale modeling framework. Molecular statics simulations were employed to evaluate the tensile and compressive behavior of Al based composites reinforced with nanosized alumina particles. Two classes of atomistic models were investigated. First, a unit-cell model containing a single Al2O3 monocrystal embedded in an aluminum matrix was used to examine the influence of the volume fraction of the ceramic inclusion on the effective mechanical properties. Second, a polycrystalline RVE model comprising an alumina particle was analyzed to assess the effect of the number of Al grains on effective properties. For each case, the mechanical response was characterized by stress-strain curves, enabling the identification of upper-scale material parameters associated with the elastic regime (bulk, shear and Young's modulus) and the damage stage (ultimate strength, ultimate strain, and failure strain). The isotropized elastic constants evaluated from molecular simulations were compared with classical Voigt-Reuss-Hill bounds to assess their applicability in the elastic regime. Finally, atomistic-scale simulation outputs provided insight into the dominant deformation/damage mechanisms (brittle versus ductile) and fracture modes (transgranular versus intergranular).

Symmetries of quantum systems provide a natural way to organize the eigenspaces of many-body Hamiltonians. When degeneracies exist, however, they play a more subtle role as different sets of symmetry operators can resolve the same energy subspace into states with very different correlation properties. We study this interplay using a sequence of FeO and Fe$_2$O$_2$ models. For a Hubbard model of FeO, the ground space is 16-fold degenerate. Resolving it by local magnetizations gives a basis of Slater determinants, while total-spin quantum numbers select entangled and non-Gaussian states from the same ground manifold. Adding density-density Hund interactions breaks the independent spin rotations and reduces the ground space to a spin-reversal pair with maximal magnetization. These states are extremely close to Slater determinants in their natural occupations, yet have finite two-body cumulants and conserved-operator algebras whose orbit dimensions differ substantially from the Slater values. Fe$_2$O$_2$ provides a larger example in which spatial mode entanglement can be substantial while fermionic non-Gaussianity remains weak, with the conserved-operator structure again distinguishing the state from the corresponding Slater transformation class. Together, these examples show that symmetry resolution, mode entanglement, reduced-density-matrix correlations, and conserved-operator structure provide complementary information about interacting and degenerate electronic ground states.

Dynamical coarse-graining of neural networks gives macroscopic observables and enables training to be predicted, and controlled in a state space far smaller than the parameter space. In this paper, we first define the learning operator following the training law of neural networks and establish a descent theorem for the learning operator, which serves to determine whether the operator is sufficient to characterize the learning dynamics. Then the exact closure theorem and the dynamic coarse-graining theorem are presented in sequence. The three theorems established in this paper provide a systematic framework for constructing and assessing dynamical coarse-grained models of neural-network training. Finally, we demonstrate the applicability of the theorems with a finite-width nonlinear ReLU network. Its dynamic coarse-grained model for a fixed pattern is exactly derived and composed of five independent moments. The model exactly predict the training outputs and evolving learning operator. The framework may also guide the development of approximate coarse-grained models for more general neural networks when exact closure is unavailable.

Wigner-negative states of light are key resources for quantum advantage in continuous-variable optical quantum computing. They can be produced probabilistically via frequency conversion and photon detection, or deterministically by exploiting the single-photon nonlinearity of a quantum emitter. Here, we generate such Wigner-negative states of light with a tunable negativity using a single semiconductor quantum dot in a cavity. Optical coherent control of the quantum-dot transition allows to generate a quantum superposition of zero and one photon. The generated quantum states are characterized point-by-point in the phase space through homodyne measurement. The emergence of Wigner-function negativity is observed as the excitation power is increased. After correcting for collection and propagation losses, we obtain fidelities to the ideal state and quantum purities above 95%, together with near-optimal quadrature squeezing. The ability to generate a wide variety of Wigner-negative states with mature semiconductor technology opens promising opportunities for continuous-variable optical quantum technologies.

Temporal hypergraphs provide an interesting representation for many social systems, as they integrate both the temporal and group nature of social interactions. Designing models of time-varying hyper-networks yields thus a convenient way to generate surrogates of empirical social systems, to understand the mechanisms underlying their emergent properties, and to investigate the evolution of dynamical processes taking place on such structures. Here, we focus on a specific and powerful class of these models, the activity-based temporal hypergraphs. We show how activity mechanisms provide control over the time scale of the dynamics, allow high modelling flexibility, and capture heterogeneity in agents' behavior. We also highlight how the activity can straightforwardly be extracted from empirical data to create surrogate datasets. We present paradigmatic examples of such models: the higher-order activity-driven models (HADx), which show that different underlying rules for the selection of active interactions produce different higher-order dynamics; the Emerging Activity Temporal Hypergraph model (EATH), able to generate surrogates of empirical systems by using higher-order mechanisms driven by both activity and group memory. We conclude discussing future perspectives for activity-based temporal hypergraphs, highlighting the potential of this framework to bridge realistic modelling of social dynamics with the study of the complex dynamical process they can support, from social contagion to opinion dynamics.

We study the thermodynamic efficiency of message-passing decoders using the mismatch cost framework. This framework quantifies the excess entropy generated when a system operates away from the thermodynamically optimal initial distribution. It provides a computable lower bound on irrecoverable energy loss. The decoder is modeled as a main decoding program with local message updates implemented as subroutines. Memory is treated as an external copying subsystem whose thermodynamic cost is excluded. Studying the $[7,4]$ Hamming code transmitted over a binary erasure channel, we show how the channel-induced initialization statistics and the step-wise evolution of the algorithmic state distribution during decoding determine the total mismatch cost. We further show that different thermodynamically optimal state distributions, representing different underlying physical implementations of the decoder, can produce different thermodynamic costs for identical decoding dynamics. Conditioning the input distribution on correctable and non-correctable erasure patterns further reveals distinct thermodynamic signatures. These results demonstrate that thermodynamic cost is jointly governed by decoding dynamics, input statistics, and hardware characteristics. This points to opportunities for thermodynamically-informed decoder design to realize energy-efficient physical implementations.

Nb$_3$Sn has the potential to exceed the performance of niobium-based superconducting radio-frequency (SRF) cavities, both in particle accelerators and in high-$Q_0$ cavities operating in multi-tesla magnetic fields for axion dark matter searches. We studied how the incorporation of Zr into the Nb$_3$Sn matrix by co-sputtering affects the microstructure and superconducting properties of Nb$_3$Sn films. As the atomic fraction of Zr increased, the surface morphology improved and the bulk and surface void densities decreased. At the optimal Zr content, the superconducting properties improved and a thinner surface niobium oxide formed. These results identify co-sputtered Nb$_3$Sn:Zr as a promising material to advance the performance limits of SRF cavities.

We study a finite-state mean-field game with entropic control cost. In the large population limit, we show that its stationary Nash equilibria satisfy the detailed balance condition and their distributions take the Gibbsian form with the value function playing the role of a Hamiltonian. We apply the entropic control cost to a ferromagnetic mean-field Ising game and investigate its stationary and non-stationary Nash equilibria. We find that the stationary Nash equilibria exhibit a second-order phase transition from disordered to ordered equilibria as temperature decreases. A center-manifold reduction yields non-stationary Nash equilibrium near the critical temperature and reveals the critical slowing down in the relaxation toward the stationary Nash equilibrium.

Open Data Analysis Tool for Science and Engineering (ODAT-SE) is an open-source Python framework for inverse problems that are solved by repeated forward simulations. It succeeds 2DMAT, which was developed for surface-structure analysis with quantum-beam diffraction and has since been applied to other fields. In version 3, the search algorithms were separated from the application-specific solvers, which became independent packages, and the software was renamed; this paper describes the current version 4.0. The framework connects optimization and sampling algorithms to solvers through a common interface for parameter mapping, constraints, and objective evaluation, so that an existing simulation code can be used with any of the algorithms. Relative to the previously published 2DMAT, it provides two-level MPI parallelism, which distributes candidate evaluations over processes and each evaluation over a parallel solver, checkpoint and continuation facilities, random search, global optimizers from SciPy, tensor-train optimization, and a Bayesian workflow that estimates partition-function ratios, model evidence, effective noise levels, and marginal posterior distributions. We validate the Bayesian workflow against closed-form results for a linear regression, benchmark tensor-train optimization on continuous, binary, and mixed-integer problems, and verify the two-level parallelization by the same optimum for all process decompositions. Taking up the positron-diffraction example of the 2DMAT paper, the workflow identifies the correlated structural solutions and an effective noise scale close to the imposed perturbation, while exposing incomplete convergence of symmetry-related mode weights. Solver packages, templates, and a gallery of examples support the use of the framework as a general platform for inverse-problem analysis.

Effective field theories (EFTs) offer a powerful method to unify diverse models under a small set of control parameters, allowing systematic expansions around well-established theories. While these techniques were traditionally developed for particle physics experiments with clean, isolated initial states, realistic macroscopic environments are often noisy and dissipative. Recognising the limitations of traditional EFTs has recently sparked intense progress at the interface of high-energy physics and condensed matter. These developments motivate a new approach to gravitation and cosmology, one that models the gravitational sector as evolving in the presence of an unobservable medium. Open Effective Field Theories provide a systematic, controllable framework for this endeavour. This chapter presents this versatile framework and illustrates how the Schwinger-Keldysh formalism captures the influence of unknown environments, manifesting as dissipation and noise, on observational probes. These notes are based on a series of lectures held during the La Ricotta Summer School "The Disordered Universe 2025" from 21 July to 1 August 2025.

These lecture notes provide an introduction to quantum spin glasses, with a particular emphasis on their application to open problems in cosmology and holography. Focusing on the spherical $p$-spin model, we develop a complete and self-contained analysis of its thermodynamic and dynamical properties. We introduce the replica method, discuss both replica-symmetric and one-step replica symmetry-broken solutions, and characterise the resulting glassy phase. The framework is then extended to the quantum model, where we study the emergence of slow dynamics and the role of quantum correlations through Euclidean and real-time correlation functions. Finally, we explore how concepts such as replica symmetry breaking and disorder naturally arise in cosmological and holographic systems related to black hole fragmentation, highlighting spin glass models as useful theoretical laboratories for these phenomena. These notes are based on a series of lectures held during the La Ricotta Summer School: The Disordered Universe 2025 from 21 July to 1 August 2025.

Recently, strong-to-weak spontaneous symmetry breaking (SW-SSB) has been established as a framework for describing quantum phases in open systems. However SW-SSB cannot be characterized by conventional charged two-point correlators. In this work, we show that, for strongly $\mathbb{Z}_2$-symmetric states with local charged involutions, SW-SSB manifests as a persistent deficit from the maximal quantum Fisher information (QFI) under symmetry-neutral pair rotations. A model-independent inequality hierarchy establishes the equivalence of this deficit with fidelity and Rényi-1 correlators as asymptotic long-range-order diagnostics. It thereby connects finite-angle state overlaps to a constraint on the infinitesimal Bures geometry along the same pair-generated orbit. For symmetry-projected Gibbs states, we further derive a lower bound on the deficit governed by the mean energy injected by the pair operation. Crucially, locality keeps this energy cost uniformly bounded in system size and endpoint separation, maintaining a finite gap below the maximal QFI at any fixed finite temperature. When ordinary charged long range order is absent, this persistent geometric constraint provides a quantitative information-geometric characterization of thermal SW-SSB.

Scientific reasoning in specialized engineering fields depends on knowledge scattered across the literature, often proprietary and absent from frontier LLM training data. In such domains, frontier models tend to give generic answers. Knowledge graphs (KGs) can ground LLM reasoning. Because a graph is too large to provide in full, typical LLM+KG systems preselect a portion, deciding relevance before reasoning begins. Here we train a compact model, Prospector, to reason over a domain knowledge graph by traversing it step by step, seeking evidence in light of what it has already found. Prospector calls a small set of tools one at a time to progressively build its context, and answers with a chain of evidence that can be checked edge by edge against what its tools retrieved from the graph. On a knowledge graph built from the semiconductor-manufacturing literature, Prospector approaches the strongest off-the-shelf models given the same graph and tools, and it far exceeds off-the-shelf models answering closed-book or from a pre-selected portion of the graph. Although trained only on the semiconductor graph, Prospector transfers to unseen knowledge graphs from three other distinct fields: bio-inspired materials, per- and polyfluoroalkyl substances (PFAS) and materials properties. Served on a single GPU, Prospector answers faster and at a fraction of the cost of a hosted service, while keeping proprietary data on the owner's hardware. We find that the policy's latent state is indicative of its next move on both seen and unseen graphs, and modulating the latent state can steer the policy from one behavior mode to another. These results suggest a practical LLM + KG paradigm for scientific and engineering reasoning over private data, in which a compact model trained on a graph from published literature transfers its traversal to unseen graphs that stay with their owners.

A technology for the in situ formation of a three-layer TiN$_x$/Ti/TiN$_x$ functional material within a single vacuum cycle is presented, together with the results of investigations of its structural and electrophysical properties. The maximum critical power density reached approximately 140 MW/cm$^2$. Under continuous operation at 90% of the critical power, the structures remained operational for 24 h. The characteristics of microbridges without and with a protective SiO$_x$ layer were compared. The presence of the coating modifies the electrothermal operating regime of the structures and enables estimated temperatures of approximately 500-700 degrees Celsius to be reached.

We compare two three-particle lattice models on the square lattice at total quasimomentum zero: three identical bosons with attractive contact interactions, and a two-fermion plus one distinguishable particle system with attractive interspecies contact. Using the Birman--Schwinger principle combined with symmetry reduction and strong-coupling asymptotics, we distinguish shared methodology from model-dependent spectral conclusions. For bosons, the ground-state energy behaves as minus three times the coupling plus six minus three over twice the coupling plus higher-order corrections, and exactly two bound states exist below the threshold for large coupling; the second lies at a finite distance 0.03542 below the threshold, a genuine eigenvalue rather than a threshold resonance. For fermions, the critical mass ratio is pi divided by pi minus two, approximately 2.75194; above it, a doubly degenerate level appears at strong coupling. Near onset, the binding energy follows a linear-over-logarithmic law. The results are compared with numerical finite-grid Faddeev computations and with recent three-dimensional classifications of threshold states.

The Disordered Universe is a novel research direction that exploits ideas and techniques coming from apparently unrelated research areas, ranging from cosmology to scattering amplitudes in particle physics and disordered complex systems, with the aim of addressing open questions in cosmology at all scales, from the very infra-red (or very late time) to the early universe. This paper acts as a general introduction and vision for a set of lectures delivered at the first La Ricotta Summer School "The Disordered Universe 2025", held from 21 July to 10 August 2025. These lectures involved open quantum systems, analytic properties of scattering amplitudes and correlation functions, foundations and quantum aspects of the de Sitter universe, as well as statistical physics out of equilibrium and spin glasses. While the lecture notes related to each course taught at the school will be published separately and are inevitably devoted to both conceptual and technical aspects of each of these topics, the school was not meant to be a collage of independent topics: the present paper has the purpose of outlining the global vision, how cosmology ends up being a unifier and benefits from both their viewpoint and techniques, how all the concepts and techniques originally coming from these four different areas are part of the same cosmological narrative, why this point of view deserves to be explored, and drawing perspectives for the future. We consider it crucial to build a microscopic theory for the early universe and maybe one that embraces all scales.

Metamaterials, which store, guide and emit waves through their eigenmodes, have enabled the development of devices with unprecedented functionalities. Yet the spatial profiles of conventional metamaterials' eigenmodes are typically determined by their pre-determined structures (Hamiltonians). In this work, we introduce `wavefunction-templated metamaterials', a class of physically realizable metamaterials hosting diverse prescribed, spectrally isolated eigenstates. The resulting Hamiltonian geometries obey a boundary law, with the required nonlocality determined solely by single-contact boundary sites, independent of the state interior or lattice size. The sparse Hamiltonians are then Hermitianized, followed by spectral reshaping to open a protective gap around the target eigenstate. We validate our approach in discrete lattices and acoustic metamaterials. Although demonstrated in acoustics, the principle can be applied to thermal, electrical-circuit and photonic metamaterials.

Feynman once remarked that the double-slit experiment has in its heart the only mystery of quantum mechanics. Arguably, the scientific significance of double-slit experiments lies in motional decoherence and the mechanism behind it. Decoherence of motional states underpins our understanding of quantum-to-classical transition. It is also central to the operation of miniaturized quantum electron devices and poses a resolution limit for electron microscopes. In this work, we provide experimental evidence for the critical role of quantum Brownian motion in electron motional decoherence. We demonstrate, for the first time, clear signatures of electron-metal decoherence and its continuous tunability. Our experiment concludes a two-decade long search for experimental realization of the Anglin-Paz-Zurek proposal, establishing electron-microchannel systems as viable open quantum platforms for free-electron quantum optics. The quantitative agreement between experiment and theory further paves the way for testing the Caldeira-Leggett quantum dissipation theory with free electrons.

Dynamical quantum simulations are commonly designed to access a particular response function or correlation function. Yet the underlying protocol prepares a family of many-body states that contains information well beyond the observable for which the simulation was originally designed. In this work, we explore the idea of using these states as laboratories for quantum information. As a case study, we consider the local-pulse protocols used to compute Green functions in finite XX and XXX spin chains, and we interpret opposite source rotations as encoding a classical bit into the many-body system. This allows us to follow how the resulting record propagates, how it is encoded across local subsystems, and how readily it can be accessed with different measurements. We also find a clear separation between representation and readout. While fermionic covariance data exactly reconstruct the signed response in the XX chain, simple spin measurements recover a larger fraction of the locally available information in the XXX chain. This reversed ordering persists when we move from finite-pulse discrimination to local source-angle estimation. Going beyond the source record, the same reduced states also allow us to reinterpret results in terms of Bell state recovery and quantum communication rates, as well as providing direct access to the evolving bipartite and genuine multipartite entanglement of the system. Our results show that dynamical quantum simulations developed for response calculations can naturally be used to ask a much broader set of quantum-information questions about the many-body states they already prepare.

We give algorithms for approximating the partition function $Z_N$ of the Sherrington--Kirkpatrick (SK) model and finite mixed Ising $p$-spin models with $p\ge 3$. The algorithms apply at a fixed margin below the second-moment threshold $\beta_{\mathrm f}$ with homogeneous weak external fields $|h|\leq\rho_0N^{-1/4}$, for fixed $\rho_0>0$. For any accuracy $\varepsilon\in(0,1)$ and failure parameter $\delta\in(0,1)$, they approximate $\log Z_N$ to additive error $\varepsilon$. The number of exact operations is polynomial jointly in $N$, $\varepsilon^{-1}$, and $\delta^{-1}$. The disorder variables have i.i.d symmetric distribution with unit variance. The failure probability is at most $\delta$ plus an explicit disorder tail bound. This tail bound tends to zero under a finite fourth moment condition. Our approach builds on the cluster expansions of Aizenman--Lebowitz--Ruelle~\cite{ALR87} and Dey--Wu~\cites{DW23,DW26}. For higher-order mixtures, we retain hypergraphs using few vertices and evaluate their total weight deterministically through local spin averages and inclusion--exclusion. For SK, we impose cutoffs on the number of vertices of degree at least three and on the total number of edges. We estimate the retained sum using randomized color coding~\cite{AYZ95}. A lower tail control based on reverse hypercontractivity~\cite{MOS13} converts the mean-square approximation of the normalized partition function into logarithmic accuracy.

We study nonlinear fluctuating hydrodynamic theories with charge and energy conservation in and above two dimensions that describe the large-scale behavior of the Hamiltonian XY model in the disordered and ordered phases. Using renormalization group analysis at one-loop order, we show that while Fourier's law holds in the ordered phase above two dimensions and in the disordered phase in any dimension, the energy diffusivity in the ordered phase exactly in two dimensions, the Berezinskii-Kosterlitz-Thouless phase, exhibits a logarithmic divergence in the thermodynamic limit. This divergence arises from elastic energy transport induced by spin-wave excitations.

The heavy fermion metamagnet uranium ditelluride possesses two distinct magnetic field-induced superconducting states. One of these superconductive phases resides at magnetic fields immediately below a first-order metamagnetic transition to a field-polarized paramagnetic state at a field strength $H_m$, while the other exists predominantly above $H_m$. However, little is known about the microscopic properties of this polarized paramagnetic state. Here we report pulsed magnetic field measurements tracking the evolution of $H_m$ for polar and azimuthal inclinations of the magnetic field in the vicinity of the crystallographic $b-a$ plane. We uncover a region of the phase diagram at high fields > 50 T with a ripple-like non-monotonic dependence of $H_m$ on the orientation of field. Within this ripple in the metamagnetic transition surface, $H_m$ exhibits an anomalous temperature dependence, implying that here the polarized state has a lower entropy than the low field paramagnetic state. Our results point towards the presence of complex magnetic interactions and possible magnetic sub-phases at high magnetic fields in UTe$_2$, which may have important implications for the manifestation of exotic field-induced superconductivity.

Magnetic skyrmions stabilized by interfacial Dzyaloshinskii-Moriya interactions (DMI) are promising candidates for applications in memory, logic, and neuromorphic computing. Beyond planar films, theoretical studies predict that curvature can influence skyrmion stability by introducing effective chiral interactions. Here, we investigate skyrmion formation on self-assembled polystyrene particles coated with Pt/Co/Ta multilayers by magnetron sputtering. Vibrating sample magnetometry reveals clear differences in the magnetic reversal behavior of the curvilinear film compared to that of the planar counterpart. Using non-invasive imaging methods such as scanning transmission X-ray microscopy and high-sensitivity in-vacuum magnetic force microscopy (MFM) with low moment magnetic tipcs, we observe a maze domain pattern for the planar films while the curvilinear film reveals three-dimensional spiraling stripe states. By employing a conventional MFM operating under ambient conditions requiring a tip with a higher magnetic moment, we demonstrate that these stripe states can rupture into metastable skyrmions located at the top of the spherical particles by applying consecutive scans. Our results demonstrate that curvilinear films offer an accessible platform for stabilizing single skyrmions using local magnetic field stimuli, opening pathways to study the interplay between interfacial and curvature-induced DMIs and enabling controlled skyrmion writing on three-dimensional magnetic architectures.

We analyze the finite-size corrections to the crosscap overlap in the two-dimensional classical Ising model along its self-dual critical line. Using a fermionic formulation, we express the lattice crosscap overlap in terms of Bogoliubov angles and develop a contour-integral approach by analytically continuing the lattice momentum to the complex plane. This leads to a remarkably simple expression for the crosscap overlap, which demonstrates that the finite-size corrections decay exponentially with system size. We further derive an exact analytical formula for the corresponding decay constant and show that it is determined by the complex singularity structure of the Bogoliubov angle.

Topological classifications of quantum critical systems have recently attracted growing interest, as they go beyond the traditional paradigms of condensed matter and statistical physics. However, such classifications remain largely unexplored in aperiodic environments, particularly under quasiperiodic modulations. In this Letter, we uncover a family of topological quasiperiodic fixed points with critical scalings intermediate between the clean and infinite-randomness limits. By exactly solving the quasiperiodic cluster-Ising chain, we demonstrate that all phase boundaries separating quasiperiodically modulated phases are governed by topological Ising-like fixed points unique to strongly modulated quasiperiodic systems. Although their local bulk critical properties match those of conventional quasiperiodic Ising critical points reported before, these fixed points host robust topological edge degeneracies and exhibit a distinct symmetry-enriched realization of the quasiperiodic Ising criticality, as further supported by complementary lattice simulations.

We investigate the formation of flat bands in a two-dimensional electron gas patterned by a periodic triangular array of repulsive antidots. In the high-barrier, narrow-trench regime, the spectrum develops kagome-like band triplets, each comprising a nearly flat band and two dispersive bands, with wave functions concentrated along the potential-free trenches. The two lowest energy bands have a different character with graphene-like dispersion and wave functions localized near the junction centers. The appearance of the trench-concentrated nearly flat bands further motivates a honeycomb quantum graph model as an effective description of the narrow-trench limit. In the single-channel graph, destructive interference produces exact flat bands with compact localized eigenstates protected by the $D_3$ symmetry. Their energies obey a quantization condition determined by propagation along the links and scattering at the junctions. We then extend the analysis to a multichannel quantum graph and derive the most general junction scattering matrix compatible with $D_3$ symmetry. Even- and odd-parity transverse channels contain equivalent symmetry sectors, and $D_3$ symmetry therefore allows them to mix. This mode conversion can disrupt the destructive interference responsible for flat bands and generically gives those bands a finite width. Exact flatness is nevertheless retained when only one transverse-parity sector is active, or when an additional symmetry forbids mixing between the two sectors. These results connect the continuum antidot model to its quantum-graph limit and identify transverse-mode mixing as a mechanism that limits flatness in multichannel networks.

Altermagnetism (AM) and its associated spin-transport phenomena are typically linked to spin-split electronic band structures in bulk materials. However, the crystal surface has a reduced symmetry with respect to the bulk, which can induce AM at the surface of conventional antiferromagnets (AFMs) $\unicode{x2013}$ a local effect which cannot be detected using bulk properties. In this work we define the symmetry conditions necessary for surface AM and show how it can be topologically protected, rendering it a robust effect. We provide a minimal model for one trivial and two topological examples of surface AM. We show that the spin spectral density, accessible by spin- and angle-resolved photoemission spectroscopy, can exhibit a $d$-wave-like altermagnetic character at the surface, even when the full band structure is completely spin degenerate. Our topological model describes the Dirac semimetal CuMnAs, which provides an existing realization of our theory. Our results identify crystal surfaces as a platform to realize robust, topology- and symmetry-driven unconventional magnetism beyond the bulk classification of magnetic materials.

We develop a hydrodynamic theory of charge and heat currents induced by traveling waves, such as surface acoustic waves, in graphene devices near charge neutrality. The currents depend on the intrinsic conductivity and viscosity of the electron liquid, the disorder strength, and the geometry of the device. We obtain analytic expressions for the heat and charge currents to second order in the wave amplitude for Hall-bar devices. At charge neutrality and in the absence of DC bias, the heat content is entrained by the wave in the absence of net charge transfer. At the same time, device conductance is enhanced by the wave. Away from charge neutrality, the transport charge current induced by the wave arises in the absence of a DC bias.

First-principles descriptions of correlated quantum materials require a simultaneous treatment of strong local many-body effects and nonlocal dynamical screening. We present an efficient fully self-consistent implementation of $GW$+EDMFT that combines nonlocal correlations at the $GW$ level with a non-perturbative treatment of local correlations within extended dynamical mean-field theory (EDMFT), with a well-defined double-counting correction and a self-consistently determined impurity interaction. Self-consistency in both the Green's function and the dynamically screened interaction is essential for describing screening processes across energy scales. A key ingredient that makes it computationally feasible is the compression of two-particle correlation functions using interpolative separable density fitting (ISDF). Applying the scheme to the Mott insulator SrMnO$_3$ and the correlated metal LaNiO$_3$, we show that the self-consistent effective local interaction resolves the overscreening inherent to constrained-RPA approaches. For SrMnO$_3$, this stabilizes a Mott-insulating state in quantitative agreement with experiment, while for LaNiO$_3$ local EDMFT corrections yield a quasiparticle mass enhancement consistent with ARPES. These results establish fully self-consistent $GW$+EDMFT as a reliable \emph{ab initio} framework for strongly correlated quantum materials.

Geological CO2 storage, geothermal energy and underground hydrogen storage depend on irreversible or high-cost decisions made with sparse data and incomplete physical understanding. Machine learning (ML) increasingly informs these decisions, yet methods are usually judged on predictive accuracy rather than on whether their outputs can be trusted, traced and acted upon. We argue that subsurface ML should be designed as decision infrastructure with shared systems that carry calibrated uncertainty and provenance from observation to operating decision. We propose a decision-readiness checklist, an audit-trail workflow for monitoring updates, and benchmark designs that score models by the decisions they support. We identify validation needs shared across the three technologies, and the data-access and governance steps needed for ML to support regulatory and investment decisions.

Microscopic heat engines operate in regimes where thermodynamic quantities fluctuate strongly, making stochastic effects an essential aspect of their performance. However, existing geometric formulations of finite-time thermodynamics primarily characterize average dissipation and do not systematically capture its fluctuations. Here, we develop a unified geometric framework that consistently describes both the mean dissipated availability and its fluctuations. In the linear-response regime, we show that these quantities are governed by metric tensors constructed from equilibrium correlation functions, providing a common geometric structure for dissipation and its fluctuations. This framework yields geometric bounds on both the mean and variance of the dissipated availability, and thereby on the efficiency and its fluctuations. The formalism applies broadly to stochastic systems, including Markov jump processes and overdamped and underdamped Brownian dynamics, establishing a unified geometric description across microscopic heat engines.

In chemically reactive environments, the mechanical integrity of geomaterials is fundamentally compromised by solid matrix dissolution. In this study, we propose a fully coupled chemo-mechanical phase-field framework to capture the dynamic interplay between mineral dissolution and fracture propagation. A key feature of the proposed model is the dynamic coupling of local mass removal to the fracture length scale, while also incorporating the damage-accelerated reaction-diffusion processes. Our results capture the development of an enlarged fracture process zone driven by chemical mass removal. This chemically induced widening blunts the sharp crack tip, alleviating the near-tip stress concentrations and causing a pronounced degradation in material stiffness before failure. Furthermore, we reveal a distinct ductilization effect, characterized by a more gradual accumulation of damage and a delayed onset of macroscopic failure. We show that the transition between brittle and ductile failure modes is dictated by the competing timescales of chemical degradation and mechanical deformation. Highly acidic environments enhance matrix dissolution and promote ductile fracture, whereas rapid mechanical loading limits chemical interaction and preserves brittle failure mode.

We consider the collisional evolution towards equilibrium of a spatially homogeneous and isotropic phonon gas of a three-dimensional superfluid with a concave acoustic excitation branch, at a non-zero but arbitrarily low temperature $T$. Three-phonon collisions $1\phi\leftrightarrow 2\phi$ are forbidden by conservation of energy-momentum. Four-phonon collisions $2\phi\to 2\phi$ of Landau and Khalatnikov lead, after a time $\propto T^{-7}$, only to a partial thermal equilibrium, a Bose law of non-zero chemical potential for the phonons, because they conserve the total number of phonons. Relaxation towards complete thermochemical equilibrium is therefore ensured by the much slower five-phonon collisions $2\phi\leftrightarrow 3\phi$ of Khalatnikov, in a time $\propto T^{-9}$. Using kinetic equations on the occupation numbers of the phonon modes and explicitly calculating the $2\phi\to 3\phi$ collisional amplitude with quantum hydrodynamics at low temperature, we determine the corresponding evolution of the fugacity $z_\phi$ of the phonon gas from the non-degenerate regime $z_\phi=0^+$ to complete equilibrium $z_\phi=1^-$. Using the conservation of total energy, we find that the fugacity varies with a non-integer power law $\propto t^{4/5}$ at short times and an exponential law at long times; the speed of change of entropy, always positive, is asymptotically proportional to the square of the speed of change of fugacity, $(\mathrm{d}/\mathrm{d}t)S_\phi\propto[(\mathrm{d}/\mathrm{d}t)z_\phi]^2$, as Landau predicted for an arbitrarily slow adiabatic transformation. Our results bring to a close the study initiated by Khalatnikov in 1950 and could be experimentally verified in a gas of cold spin-1/2 fermionic atoms in the sector of the BEC-BCS crossover where the acoustic branch has a concave start, or in superfluid liquid helium-4 at sufficiently high pressure.

Collective excitations in fermionic systems play a crucial role in determining their physical properties. An important challenge is to develop efficient theoretical approaches for describing these excitations and their coupling to fermionic degrees of freedom. In this work, we revisit the problem of quantifying the contributions of individual bosonic modes of collective fluctuations to observable properties of correlated fermion systems within the framework of the Fluctuating Local Field (FLF) method. Whereas the auxiliary field in this method was previously considered only classically, we formulate its systematic extension termed Quantum FLF (Q-FLF) that incorporates selected bosonic Matsubara modes, thus tailoring it to description of quantum collective fluctuations. As a testbed, we apply the approach to a half-filled one-dimensional Hubbard chain and compute the Green's function, the total energy, and the antiferromagnetic susceptibility. Our results demonstrate that the proposed scheme enables an efficient and selective characterization of the contributions of individual bosonic modes. In particular, low Matsubara frequencies are found to have a quantitative impact on integrated observables such as total energy and antiferromagnetic susceptibility. At the same time, an accurate description of single-particle properties requires inclusion of higher-frequency bosonic modes.

The generation of transverse voltage in superconducting thin films carrying a longitudinal current has been recently related to demonstrate exotic, symmetry-breaking transport phenomena. To understand the underlying phenomenon we chose two distinctly different systems to investigate; a conventional (Nb) and a nonconventional (Ni/Bi bilayer) superconductor. A systematic study of this transverse response in these type-II superconducting thin films we aimed towards establishing its microscopic origin. Both longitudinal and transverse magneto transport measurements were carried out with Hall-bar patterned devices as a function of temperature with magnetic field applied out-of-plane. In both systems, a sharp, field antisymmetric transverse resistance emerges in the superconducting transition region, closely following the field derivative of the longitudinal resistance while it was vanishingly small or absent in the fully superconducting or normal states. Based on the vortex-flow model, the behavior could be quantitatively attributed as the transverse voltage arising due to the motion of Abrikosov vortices under a combined action of Magnus like force and viscous drag force, rather than from any exotic or intrinsic Hall-type mechanism. The close correspondence between a nominally conventional superconductor Nb and an unconventional superconductor heterostructure incorporating a ferromagnetic layer indicates that the vortex dynamics alone, independent of magnetic proximity effects or unconventional pairing, seems to be sufficient to account for the observed transverse signal. Our observations while seems to provide a quantitative, material-independent model for interpreting transverse voltages in superconducting films, raises the concerns in attributing such signals to exotic physics without first ruling out conventional vortex-flow contributions.

The superconducting diode effect manifests as nonreciprocal properties of critical currents, yet a systematic tensorial framework for its symmetry-governed responses remains lacking. We develop such a framework by relating the angular harmonics of critical currents to the magnetic field. Crystalline symmetries constrain the dipolar response to be purely antisymmetric (Hall-like) in Rashba superconductors with $C_{3v}$, $C_{4v}$, or $C_{6v}$ symmetry, whereas they require a diagonal, traceless tensor in Dresselhaus superconductors with $D_{2d}$ symmetry. For systems with fourfold symmetry, the octupole response appears at linear order, whose response tensors take symmetric off-diagonal and identity forms for $C_{4v}$ and $D_{2d}$ symmetries, respectively. Furthermore, nematicity activates otherwise forbidden tensor components, providing a sensitive probe of rotational symmetry breaking in superconductors. At cubic order in the magnetic field, the nonlinear response tensors likewise exhibit distinct symmetry-dependent patterns. Our framework establishes a symmetry-resolved characterization of the superconducting diode effect and provides a route to probing the underlying electronic structure and symmetry-breaking orders.

We theoretically study the non-Hermitian topology of magnons with finite lifetimes due to Gilbert damping. By incorporating the spin-wave theory and perturbation theory for the Landau-Lifshitz-Gilbert equation including nonlocal damping terms, we analytically evaluate the spectral winding number for point gaps, which indicates the existence of the non-Hermitian skin effect (NHSE). We find that, in noncollinear magnetic textures, the NHSE can occur even in the absence of nonlocal damping, due to the momentum-dependent mixing of the particle and hole components of magnon eigenmodes, which is absent in collinear magnets with a single magnon band. In the presence of nonlocal damping along one direction, we show that the winding number for an energy band with a unique minimum is determined from the sign of the wave number at the band minimum. We demonstrate these results using a model that hosts a skyrmion-string lattice as a steady state. We further investigate spin-wave propagation dynamics excited by a magnetic-field pulse and show that the propagation direction changes drastically from band to band depending on the presence of local and nonlocal damping, consistent with the nontrivial winding numbers.

Crossed Andreev reflection (CAR) is a nonlocal quantum transport phenomenon that arises at the interfaces between a superconductor and two spatially separated metals. In this process, an electron incident from one metal combines with another electron originating from the other metal to form a Cooper pair in the SC. In this work, we theoretically investigate the quantum transport properties of a device comprising a central $s$-wave superconductor sandwiched between two bipolar magnetic semiconductor (BMS) leads. BMS materials possess a unique bandstructure where the conduction and valence bands are fully spin-polarized in opposite directions. By applying independent gate voltages to the two BMS leads, we selectively tune their chemical potentials to configure an antiparallel spin alignment at the Fermi energy. In the absence of spin-orbit coupling (SOC), this specific configuration perfectly suppresses both local Andreev reflection and direct electron tunneling (ET), thereby isolating and profoundly enhancing CAR. The introduction of Rashba SOC, however, induces spin-flip scattering that relaxes these strict selection constraints, yielding finite probabilities for competing scattering channels and subsequently reducing the overall CAR efficiency. Nevertheless, for SOC strengths below a critical threshold, CAR remains the dominant transport mechanism over ET. This proposed architecture provides a scalable, stray-field-free method to achieve purely electrostatic control over nonlocal transport, advancing the development of highly efficient superconducting spintronic devices.

Determining the spin Hamiltonian of a magnetic compound is crucial for understanding its magnetic properties. A standard approach is to derive model parameters from ab initio calculations based on the crystal structure. However, the resulting Hamiltonian can depend sensitively on methodological details of the ab initio procedure. This issue is particularly evident in $\alpha$-RuCl$_3$, a candidate Kitaev material. Here, we present an alternative, data-driven approach to determine the spin Hamiltonian parameters of $\alpha$-RuCl$_3$ by Bayesian optimization of experimental magnetization curves along the $b$- and $c$-axis directions. We optimize five parameters, namely the Kitaev interaction $K$, off-diagonal interactions $\Gamma$ and $\Gamma'$, the Heisenberg interaction $J$, and the $c$-axis $g$-factor $g_c$. The parameter set that minimizes the cost function is $(K,\Gamma,\Gamma',J,g_c)=(-6.0, 7.5, -0.3, -1.75, 2.3)$, where the exchange couplings are in meV. We find that the cost function is insensitive to the absolute value of the Kitaev coupling $K$. Thus, the magnetization data alone do not determine its energy scale. The cost function also depends only weakly on $\Gamma'$ and $J$, while the optimization favors a large positive $\Gamma$. By computing the static spin structure factor, magnetic susceptibility, and specific heat, we show that these quantities favor the large-$\Gamma$ scenario over the small-$g_c$ scenario and that the parameter set that minimizes the cost function yields good agreement with the experimental structure factor and susceptibility, and qualitative agreement with the specific heat. The combination of Bayesian optimization and accurate low-energy solvers provides an effective approach for determining parameters of spin Hamiltonians. This methodology opens a systematic route to determining spin Hamiltonians in quantum magnets from experimental data.

Hall viscosity on a lattice depends on how strain changes microscopic hopping amplitudes. For a specified Gaussian envelope, bond-length derivatives close on the undeformed hopping, expressing the stress as an embedded momentum Hessian and relating the viscosity to higher-order band geometry. In the Kapit--Mueller parent family at rational flux, we show that the stress response equals the strain curvature of the sampled-LLL Gram matrix. The density-normalized viscosity approaches the continuum value 1/4, with an exponentially small sampling correction at finite flux. By contrast, for a straight-bond Peierls source, a low-frequency mass, and a fixed-envelope susceptibility, the viscosity--conductivity comparison exhibits an algebraic deviation, whose leading coefficient follows from a weak-field expansion.

Catalyst discovery for green hydrogen has optimized activity alone, deferring economic and environmental costs to stages where they disqualify otherwise promising candidates. Here we introduce a unified machine learning framework that screens catalytic activity and monetized carbon cost in a single pipeline. A machine learning potential predicts hydrogen evolution activity and stability at density-functional-theory accuracy. A second model, trained on published estimates of the social cost of carbon, converts each candidate's embodied CO2 into a monetary burden. Screening 460 graphene-supported dual-atom catalysts across 23 transition metals and 20 nitrogen-coordination motifs yields 26 active, synthesizable candidates. The two axes then conflict. The most active candidates span Mn-, Fe-, Zr-, Cr-, Cu-, Ni-, Ti-, Nb-, V-, Pd-, Au-, and Rh-based catalysts, indistinguishable in adsorption energy yet spanning a 58,000-fold range in carbon cost. Joint optimization selects Mn2@2Nf and Zr2@2Nc, matching the best precious-metal activity at tens-of-thousands-fold lower carbon cost, independent of catalyst loading.

We investigate the metal-insulator transition driven by the onsite repulsive interaction $U$ in an altermagnetic Hubbard model defined on a Lieb lattice. Using the slave-rotor approach at half-filling, we find that the system exhibits a cascade of interaction-driven phase transitions. As $U$ increases, the system evolves from a normal metal to an altermagnetic metal, then to an altermagnetic insulator, and eventually to an altermagnetic Mott insulator characterized by the complete suppression of the quasiparticle weight. These phases are supported by the calculation of the electronic spectral function, which features spin-split bands in both the metallic and insulating regimes. However, the spin splitting becomes substantially suppressed in the Mott-insulating phase. Our results suggest that the observation of spin splitting in the spectral function of $d$-wave altermagnets with a Lieb-lattice-like structure may be limited to the weak-to-moderate correlation regime.

Condensable algebras in 2+1d non-chiral topological orders characterize gapped boundary conditions and interfaces. Applied to the Symmetry Topological Field Theory, they allow classification of symmetric gapped phases and impose sharp constraints on possible phase transitions. A condensable algebra is specified not only by its underlying set of anyons, which end on the boundary or interface, but also by its algebra structure. We introduce the concept of twin condensable algebras, which have the same anyon decomposition, but inequivalent algebra structure. We revisit the classification of condensable algebras in $\mathcal{Z}(\text{Vec}_G^\omega)$, i.e. in group-theoretical topological orders for finite groups $G$ with anomaly $\omega$. In this context we are able to identify twin algebras that arise from different mechanisms, such as subgroup data, SPT cocycles, and symmetry actions. In particular, we construct infinite families of examples of twins from so-called Gassmann triples, and exhibit cases in which the reduced topological orders are inequivalent despite having identical anyon content. Physically, twin algebras describe distinct symmetric phases that have isomorphic spaces of ground states, but inequivalent order parameters. Such twin phases never exhibit relative spontaneous symmetry breaking, and can be used to construct phase transitions without hidden symmetry breaking, which are intrinsically beyond Landau transitions.

"Infinite layer" nickelates ${\cal R}$NiO$_2$ (${\cal R}$=rare earth), having empty apical O sites, become superconducting upon hole doping, stimulating research into the related sequence Nd$_{n+1}$Ni$^{+p}_n$O$_{2n+2}$, formal charge state $p$=1+$\frac{1}{n}$, $n$=2,3,4,...., with the $n$=5 member being found to be superconducting. The two layer system La$_3$Ni$_2$O$_{7-\delta}$, with $\delta$=0,$\frac{1}{2}$,1 ($p$=2.5,2,1.5) approaches the peak in the nickelate superconducting dome but shows no superconductivity. Newly reported La$_3$Ni$_2$O$_5$F reaches the Ni$^{1+}$ goal while, as we show, introducing a partially occupied electron band $E^*$, based on an interstitial density that extends over the three open "apical" layers and leads to a single cylindrical electron Fermi surface giving self-doping. The commonly inert Ni $d_{xz},d_{yz}$ orbitals partner with interstitial $E^*$ to provide an incipient non-analytic Dirac point, with the critical point being reachable by pressure or further F insertion. The $E^*$ electron cylinder and the conventional Ni $dp\sigma$ hole carriers combine to provide a two-fluid dichotomy of hole and electron quasiparticles, affecting normal state properties that should verify the dichotomous aspect of transport.

Dispersive coupling between vibrational modes with different frequencies is a major nonlinear dynamical effect. We show that in $p$-doped semiconductors such coupling is strongly enhanced. Moreover, the coupling parameters increase with the order of the nonlinearity. The doping-induced dispersive coupling becomes much stronger than the intrinsic one already for moderately strong doping. Its dependence on the hole density is nonmonotonic, and the temperature dependence becomes nonmonotonic for higher densities. Relevant mesoscopic frequency fluctuations are briefly discussed. The results are applied to Si resonators, where doping is used to compensate the temperature dependence of a clock mode, whereas another low-frequency mode is used as a thermometer to enable temperature stabilization.

Antiferromagnetic skyrmions are swirling topological spin textures with rich dynamics and intriguing transport properties, yet their bidirectional dynamics remain largely unexplored. Here, we investigate the dynamics of antiferromagnetic skyrmions driven by current-induced spin-transfer and spin-orbit torques. We computationally demonstrate that antiferromagnetic skyrmions moving in one direction at low current densities can reverse their motion direction when the driving current is above a threshold. Based on the Thiele approach analysis, we show that this bidirectional motion originates from a change in the relative strengths of two effective forces arising from spin-transfer and spin-orbit torques. Furthermore, exploiting this bidirectional motion on a single racetrack, we design programmable logic gates. Our results not only uncover a hidden mechanism for bidirectional skyrmion motion but also facilitate the development of antiferromagnet-based logic devices.

Relative motion between interacting systems can generate emergent energy scales that are absent in isolated systems. While uniform motion can be eliminated by a Galilean transformation, relative motion between interacting systems generally cannot. By coupling to an excitation's spatial structure, relative motion generates a Doppler frequency determined by its wavevector and the relative velocity, providing a mechanism for driving nonequilibrium phenomena. In this tutorial, we illustrate these ideas using magnonic systems as a concrete platform. We first discuss motion-induced magnon transport between relatively moving ferromagnets, in which the Doppler frequency serves as an effective nonequilibrium bias in the perturbative regime. This mechanism produces magnon currents even without conventional driving forces such as temperature gradients or chemical potential differences. We then introduce motion-induced parametric instabilities. When the emergent scale becomes sufficiently large to resonantly create magnon pairs, the perturbative description breaks down, and the magnonic vacuum becomes unstable. This instability occurs above a critical velocity threshold and leads to spontaneous magnon-pair creation. Connections to related phenomena, including quantum friction, Cherenkov emission, and Zel'dovich superradiance, are also highlighted. The concept of an emergent energy scale provides a unifying framework for understanding transport phenomena and instabilities in quantum systems with relative motion.

We study scattering in noninteracting multi-terminal quantum wire junctions and show that junctions with dihedral symmetry can exhibit exact zero-reflection points for $N \ge 4$ terminals. By analyzing the scattering matrix, we identify these reflectionless points in the $(E,t')$ parameter space, where $E$ is the incident particle energy and $t'$ is the junction hopping amplitude. These points exhibit an even-odd dependence on $N$ and converge asymptotically to a common limiting value in the large-$N$ limit. We show that the reflectionless points are characterized by an integer winding number associated with the phase of the reflection amplitude, providing a topological description for their stability against weak on-site disorder. We also consider junctions with broken time-reversal symmetry and find that a magnetic flux can induce additional reflectionless points, including for the $N = 3$ case. For a four-terminal junction threaded by a $\pi$-flux, we identify a unique parameter regime in which the reflection amplitude vanishes over the entire energy band. Finally, we discuss experimental signatures through the behavior of Friedel oscillations and examine the stability of these reflectionless points in the presence of weak interactions.

Altermagnetic order gives rise to momentum-dependent spin splitting of electronic and magnonic excitations even in the absence of a net magnetization. Here, we investigate the magnetic field dependence of the spin-wave spectrum of altermagnetic $\alpha$-MnTe using inelastic neutron scattering and linear spin-wave theory. An in-plane magnetic field continuously reorients the Néel vector by overcoming the weak crystalline anisotropy, while remaining small compared with the dominant exchange scale. We find that this reorientation leaves the magnon energies and line widths essentially unchanged, but strongly modifies the measured spectral intensity through the transverse-momentum projection. Our results demonstrate a clear separation between the soft orientational degree of freedom of the antiferromagnetic order and the robust exchange-dominated chiral magnon spectrum. This combination establishes $\alpha$-MnTe as a platform for reconfigurable magnon coupling, in which external fields tune how excitations interact with polarized probes without substantially altering their frequency or coherence.

We show the emergence of a quantum fluctuation-driven transport crossover between two liquid states in distinguishable helium-4 obeying Boltzmann statistics, in the absence of atomic exchange. Using path integral centroid molecular dynamics simulations over 0.1-3.3 K and 1-60 bar, we investigate the transport properties of two distinct liquid states: the low quantum dispersion liquid (LQDL) and the high quantum dispersion liquid (HQDL). While LQDL exhibits conventional liquid behavior consistent with the Stokes-Einstein (SE) relation, HQDL emerges at lower temperatures and displays anomalous gas-like transport characterized by superdiffusion and ultralow viscosity, accompanied by a breakdown of the SE relation. This counterintuitive emergence of gas-like dynamics upon cooling reflects the dominant role of nuclear quantum fluctuations, in contrast to thermal fluctuations at higher temperatures. Across the LQDL-HQDL boundary, we identify a transport crossover marked by a qualitative change in the velocity autocorrelation function (VAF), a transition in the Prandtl number, and the emergence of transport minima in shear and kinematic viscosities, thermal conductivity, and thermal diffusivity. These minima reflect a crossover from liquid-like to gas-like transport upon cooling in the low-temperature subcritical region, in addition to the universal transport minima observed in the supercritical regime. The transition from oscillatory to monotonic VAF defines a second Frenkel line, distinct from the conventional Frenkel line observed in the supercritical region. LQDL is a heat-transport-dominated dissipative fluid, whereas HQDL is a momentum-dominated inertial fluid. These results demonstrate that nuclear quantum fluctuations alone induce gas-like liquid behavior and provide a unified picture of transport phenomena in distinguishable helium-4 without superfluidity.

Amorphous refractory metal coatings combine high hardness with chemical inertness, yet their metastability makes them prone to mechanically induced crystallisation (devitrification) under contact loading, and how readily such a glass re-orders to its parent body centred cubic (bcc) crystal is unknown across the refractory series. We prepared amorphous V, Nb, Mo, Ta and W by melt quenching to 300 K, benchmarked each interatomic potential against ab initio liquid radial distribution functions and self-diffusion coefficients, and probed them by large scale molecular dynamics nanoindentation. Indentation drives a localised amorphous to bcc transformation by bulk nucleation, growth and coalescence. A crystal forming ability (CFA), the maximum slope of the sigmoidal bcc fraction versus depth curve, spans about a factor of four and decreases as V > Mo > Nb > Ta > W; it falls with indenter velocity as CFA scales as v^(-m), with a mean exponent of 1.08, so CFA.v is nearly constant and the transformation rate is almost velocity independent. Transforming atoms carry excess non affine displacement and local shear strain, not hydrostatic pressure, marking a shear associated displacive pathway; the bulk driving force is largest for the most resistant element, W, so resistance tracks cohesive bond strength rather than the thermodynamic driving force. Early bcc like order correlates with the sharpness and depth of the transition, whereas the mechanical work to half transformation correlates with the peak density of persistent bcc clusters. A cluster population balance links nucleation, growth and coalescence to a terminal microstructure whose completeness does not follow the CFA order.

In ordered intermetallics, slight variations in lattice site occupancy and specific interlayer spacings have been identified as the sources of significant changes in critical resolved shear stress and therefore how a given phase may affect alloy properties. So far, atom positions and lattice site occupancies have traditionally been characterised by high-resolution transmission electron microscopy (HR-TEM) and X-ray diffraction (XRD), which are methods that offer either local detail or high statistical significance but not both. Electron backscatter diffraction (EBSD), by contrast, provides high spatial resolution across large sample areas and therefore, has the potential to enable the local investigation of interlayer spacing and site lattice occupancy with improved statistical reliability. The objectives of the study are to benchmark EBSDs capability for resolving these subtle features and to correlate them with compositional and mechanical properties. In this case study, we therefore show that EBSD can resolve key crystallographic features of mu-phase intermetallics, specifically interlayer spacings. We combine pattern matching with large-scale dynamical simulations of template libraries guided by XRD based information on lattice parameters. For this, we generate structures that vary in the spacing between triple-layer and Kagome layer and in the site lattice occupancy of the 3a site. This approach successfully predicts the change of interlayer spacing between Kagome and triple layers in Nb-Co and Nb-Ni mu-phases, in good agreement with XRD and HR-TEM.

Thermal transport offers a bulk probe of charge-neutral excitations in frustrated magnets. It remains challenging, however, to determine whether such transport can distinguish different parton mean-field structures of the same spin system. This question is particularly relevant on the honeycomb lattice, where distinct $0$-flux, $\pi$-flux, and chiral $\pi/2$-flux sectors have been proposed. In this paper, we compare self-consistent saddle-point solutions in these three sectors for a frustrated $J_1-J_2$ Heisenberg model with a next-nearest-neighbor Dzyaloshinskii-Moriya interaction and a perpendicular magnetic field. Using finite-temperature Schwinger-boson mean-field theory and the Kubo formula for bosonic Bogoliubov-de Gennes systems, we evaluate the intrinsic spinon thermal Hall conductivity. At a common parameter point where all three branches remain gapped, the $0$-flux response is positive and the $\pi$-flux response is negative for $D>0$ and $h>0$ under the sign conventions used in this paper, whereas the $\pi/2$-flux response changes sign with increasing temperature. We further show that a projective symmetry combining a sixfold rotation with time reversal forces the zero-field response of a fixed chiral $\pi/2$-flux domain to vanish. Within the mean-field regime examined in this paper, the sign and temperature dependence of $\kappa_{xy}/T$ therefore provide a flux-sensitive transport signature.

The degradation of LiNi$_{0.8}$Co$_{0.1}$Mn$_{0.1}$O$_2$ (NCM-811) in Li-ion batteries produces complex transition-metal oxides and binary phases that fundamentally limit cathode performance. While identifying these degradation products via X-ray absorption spectroscopy (XAS) is essential for mitigating electrochemical performance loss, interpretation remains challenging due to the structural complexity of real-world samples. In this work, we present an integrated theoretical-experimental framework combining high-resolution oxygen K-edge XAS with \textit{ab initio} simulations based on many-body perturbation theory and high-throughput screening from density functional theory. We first evaluate the spectroscopic fingerprints of eight layered, spinel, and nominal rock-salt reference oxides, identifying discrepancies between the idealized single-crystal bulk phase and experimental spectra. Using high-throughput screening to analyze the oxygen $p$-projected density of states of 38 distinct polymorphs of NiO, CoO, and MnO, we propose that the spectral differences can emerge, among other factors, from local structural variations represented here by simplified structural proxies. Our work establishes a viable and rigorous computational pathway to interpret the complex landscape of degraded battery materials.

We study the retrieval dynamics of an $n$-body asymmetric dense associative memory model, in which sequential retrieval is implemented by shifting one pattern index in the higher-order Hebbian interaction. The model exhibits sequential retrieval of the stored patterns, and the retrieval state corresponds to a stable limit-cycle attractor. The storage capacity is defined as the maximum loading rate for which this limit cycle remains stable. Using generating functional analysis, we derive the dynamical equations describing the sequential retrieval state. The generating functional analysis reveals that the retarded self-interaction term vanishes in the asymmetric model, and the resulting overlap dynamics is reproduced by an Amari-Maginu-type signal-to-noise analysis. Also, we find that for the interaction order $n\ge 3$, the normalized storage capacity decreases monotonically with increasing interaction order, in contrast to symmetric Modern Hopfield models.

Odd slip at solid-liquid interfaces, characterized by a velocity component perpendicular to the applied shear stress, introduces a novel class of odd transport phenomena with transverse momentum transfer at boundaries, distinct from odd viscosity, odd elasticity, or odd diffusivity. This effect arises on chiral active surfaces with persistent energy input and defined handedness, such as carpets of rotating biological or synthetic cilia with flexible anchoring. Although odd slip itself is dissipationless, its maintenance in active systems comes at an energetic cost, which we estimate from the microscopic model. With respect to its orientation dependence, odd slip can be classified as pseudo-scalar or pseudo-vectorial. We use a perturbative expansion to determine the resistance tensors of problems with different levels of broken symmetries. They reveal how the surface chirality and body asymmetry together violate the Onsager symmetry, but uphold the Onsager-Casimir reciprocity. Strikingly, suspensions of particles with odd slip embedded in a conventional Newtonian bulk fluid exhibit odd viscosity, providing a new minimal mechanism for its emergence beyond current microscopic models.

An empirical comparison of high resolution M4,5 X-ray Absorption Spectroscopy (XAS), based upon High Energy Resolution Fluorescence Detection (HERFD), with Bremsstrahlung Isochromat Spectroscopy (BIS), the high energy variant of Inverse Photoelectron Spectroscopy (IPES), of various actinide materials is presented here. It will be shown that XAS-HERFD is essentially the j-specific version of BIS, providing a direct measure of the separate 5f5/2 and 5f7/2 Unoccupied Density of States (UDOS).

A solvable microscopic model of interacting electrons in a half-filled Landau level is presented. The Hamiltonian is a well-defined limit of the electron-electron interaction. The low energy sector consists of a set of independent, spatially interlaced, one-dimensional systems of non-interacting fermionic dipoles, each system with a Fermi sea ground state. The total number of dipoles in the set of Fermi seas forming the two-dimensional ground state equals the number of electrons in the system and the density of states at the Fermi level is that of a two-dimensional Fermi gas. The model is obtained by generalizing, or rather adopting, the existing exact solution on a thin, but not too thin, torus to the two-dimensional bulk case.

We develop a bootstrap approach to deriving lower bounds on the spectral gap of the first Haldane pseudopotential Hamiltonian on the sphere with $N_\Phi$ flux quanta for arbitrary $N_\Phi$, including in the thermodynamic limit $N_\Phi \to \infty$. This method can in principle be generalized to pseudopotentials describing other model wavefunctions such as the Moore--Read state or Read--Rezayi sequence. Our approach is based on Knabe's observation that if $H$ is a Hamiltonian with ground state energy zero then the spectral gap is at least $\epsilon > 0$ if and only if $H^2 \succeq \epsilon H$. To show this inequality, we split $H^2$ into two parts, one that can be analytically bounded and another that can be bounded using a finite semidefinite program (SDP). Crucially, the size of this program is determined only by cutoff parameters, and the program depends on $N_\Phi$ only parametrically, allowing us to obtain numerically exact (up to solver precision) lower bounds on the gap. In order to turn these numerical bounds into mathematically rigorous results, we introduce an algorithm that can produce nearly-optimal exact interior feasible points for large rational SDPs even if the affine constraints are highly redundant and ill-conditioned. We additionally provide an algorithm that establishes the rank stability of the SDP in the $N_\Phi \to \infty$ limit, which is needed to certify the bound in the thermodynamic limit. Beyond establishing a Laughlin gap greater than $1/100$ in the thermodynamic limit and revealing a potential method for deriving spectral gap lower bounds for other pseudopotentials, our work provides a general method for turning numerical SDP bounds into rigorous mathematical proofs, which may have wide applicability. In particular, this work demonstrates that bootstrap methods can be used to rigorously resolve major open problems in quantum many-body physics.

Compression can enhance or suppress cell motion and induce coherent rotation in tissue spheroids, but the physical factors governing these responses remain unclear. Using a minimal three-dimensional active vertex model, we examine how tissue mechanics, active driving, and directional alignment shape the response to uniaxial compression. Without alignment, compression enhances transverse motion in solid-like spheroids throughout the tested activity range, whereas fluid-like spheroids switch from acceleration at low activity to slowing at high activity. Changes in contact persistence connect these responses to neighbor exchange. Passive five-cell calculations show that compression reshapes local rearrangement barriers depending on geometry and loading direction; a high-strain increase in the fluid-like mean coexists with many low-barrier paths. With strong alignment, compression induces coherent rotation in solid-like spheroids, while fluid-like spheroids show no comparable rotation. Rotating solids retain more persistent cell contacts than fluids and develop tangential organization of peripheral cells. Controlled perturbations reveal that compression softens a differential-twist mode and activity slows its relaxation. Together, these results link activity-dependent reversal of the speed response and compression-induced coherent rotation to contact dynamics, local rearrangement costs, and active driving. Our findings demonstrate that one minimal model, with parameters representing effective mechanical and active tissue properties, captures diverse collective responses to compression and provides a framework for predicting how different tissues respond to mechanical loading.

Accurate and efficient prediction of lattice thermal conductivity (LTC) is essential for developing materials for thermoelectric, microelectronic, and photovoltaic applications. Here, we present a methodology for high-throughput calculation of LTC across large datasets of compounds sharing a common crystal symmetry. Our approach combines fine-tuning of the MatterSim 1M universal machine-learned interatomic potential with LTC calculations based on the solution of the Boltzmann transport equation. We introduce a symmetry-based few-shot fine-tuning strategy (SBFS-FT) based on low-rank adaptation. In this approach, MatterSim 1M is fine-tuned on a small, carefully selected set of compounds that share a common crystal symmetry. The resulting potential is then applicable for accurate LTC calculations for compounds with this crystal symmetry, even if they were not included in the fine-tuning set. We tested our methodology on datasets of half-Heusler compounds (space group 216), materials with space group 225, and spinels (space group 227). We demonstrated that LTC calculations with MatterSim 1M fine-tuned using SBFS-FT exhibited a mean absolute relative difference from the reference results (obtained using moment tensor potentials and polyMLPs) 2-3 times smaller than that achieved with the non-fine-tuned MatterSim 1M potential. Moreover, the accuracy of LTC calculations with MatterSim 1M after SBFS-FT was comparable to that achieved using the MatterSim 1M potentials individually fine-tuned for each compound. Importantly, SBFS-FT enabled generation of the potential suitable for accurate LTC calculations across large compound datasets substantially faster than fine-tuning of MatterSim 1M for each compound individually, reducing the computational time by approximately a factor of 5-7 for a dataset of 100 compounds.

We present a lattice gas model with random interactions quenched in space and spins quenched to the particles. The vacancy-mediated diffusion is studied in equilibrium. A two-stage slowdown is witnessed in both the mean squared displacement and the spatial overlaps. We demonstrate that the plateaus are due to anti-correlation at the corresponding length scale. The anti-correlation diminishes quickly with increasing lag time. A broad and yet finite distribution of the survival function of vacancies suggests their normal diffusion at large time limit. Our model can serve as a new playground for understanding hierarchical dynamics in glassy-like dynamical systems.

The two-dimensional Hubbard model was originally proposed as the minimal model of uniform $d$-wave superconductivity in the cuprate high-temperature superconductors, but recent calculations with relevant parameters in a realistic doping regime have often found other ground states. Further, uncertainty remains over such results due to the intrinsic bias of different computational methods. Here we address this uncertainty through state-of-the-art neural tensor network and neural backflow state simulations, enabled by large-scale GPU computation, that together reach an unprecedented variational accuracy on lattices with up to 1024 sites. At $1/8$ doping in the pure Hubbard model, as well as with next-nearest-neighbor hopping relevant to the hole-doped cuprates, we reveal a near degeneracy among a low-energy uniform $d$-wave state, superconducting stripes, and non-superconducting stripe states on the milli-$t$ energy scale. Our work rebalances the narrative that the Hubbard model supports a single dominant order in relevant parameter regimes towards a picture of extreme competition between stripes and superconductivity.

We study a sluggish random walk, whose diffusivity decreases as a power law with distance from the origin, under Poissonian resetting to the origin. Using a mapping to a signed Bessel process and renewal theory, we obtain exact results for the maximum trajectory value in a finite window, the time at which it occurs, and the time of the last visit to the origin. Resetting changes the growth of the typical maximum from a power law in time to a power of its logarithm. The centered maximum approaches a Gumbel law, whose width shrinks in physical space for any positive sluggishness exponent, unlike the Brownian case. In the Bessel coordinate, the probability that the maximum exceeds a value growing in proportion to the observation window length decays exponentially, with a rate that has a second-order dynamical transition and is independent of sluggishness. The time of the maximum is uniform in the bulk, with boundary layers that shift its mean above the midpoint logarithmically with window length. The time since the last visit to the origin follows a Gamma law with a sluggishness-dependent shape. Reflection symmetry makes the last-visit time uncorrelated with the occupation time of the positive half-line.

A bound state in the continuum (BIC) is a spatially localized energy eigenstate embedded in a continuous spectrum of extended eigenstates. While diverse types of single-particle BICs have been reported in the literature, understanding how such localization persists in interacting many-body systems remains a fundamental problem. Here, we present numerical evidence and a perturbative analysis supporting the existence of many-body BICs in a one-dimensional Bose-Hubbard chain with an attractive impurity potential, a system previously known to host a BIC in the two-particle sector. Furthermore, we demonstrate that the Bethe-type construction of the known two-particle BIC breaks down already for three particles even for arbitrary finite superpositions of Bethe waves. The resulting BICs violate the eigenstate thermalization hypothesis for several local one- and two-body observables, leading to nonthermal dynamics from experimentally accessible initial states.

We investigate nonstabilizerness, also known as ``magic,'' to understand criticality and exceptional points in non-Hermitian quantum many-body systems. Our focus is on parity-time ($\mathcal{PT}$)-symmetric spin chains, specifically the non-Hermitian transverse-field Ising and XX models. We calculate stabilizer Rényi entropies in their ground states using non-Hermitian matrix product state methods. Our findings show that magic exhibits unique and model-specific signs of phase transitions. In the Ising chain, it peaks near the regular Hermitian-like critical line but disappears across exceptional points. In contrast, in the XX chain, it reaches its maximum at the exceptional line where $\mathcal{PT}$ symmetry is broken. Finite-size scaling reveals that these effects become more pronounced with larger systems, highlighting nonstabilizerness as a sensitive marker for both quantum criticality and non-Hermitian spectral degeneracies. We also investigate magic in momentum space for the XX model analytically and find that it reaches a minimum around exceptional points. Our results indicate that magic takes extremal values at the exceptional points and serves as a valuable tool for examining complexity, criticality, and symmetry breaking in non-Hermitian quantum matter.

Large language model (LLM)-driven agents are emerging as a powerful new paradigm for solving complex problems. Despite the empirical success of these practices, a theoretical framework to understand and unify their macroscopic dynamics remains lacking. This paper proposes a method based on the least action principle to estimate the underlying generative directionality of LLMs embedded within agents. By experimentally measuring the transition probabilities between LLM-generated states, we report evidence consistent with a tendency toward detailed balance in LLM-generated transitions, indicating that LLM generation may not be achieved by generally learning rule sets and strategies, but rather by implicitly learning a class of underlying potential functions that may transcend different LLM architectures and prompt templates. To our knowledge, this provides an effective macroscopic description of LLM generative dynamics that does not depend on specific model details. This work is an attempt to establish a macroscopic dynamics theory of complex AI systems, aiming to elevate the study of AI agents from a collection of engineering practices to a science built on effective measurements that are predictable and quantifiable.

The origin of the anomalous magnetic fields of Uranus and Neptune, with significant tilts and multi-dipole configurations, is central to understanding the internal structure and evolution of the ice giants. Recent investigations confirmed that superionic H$_2$O ice is thermodynamically stable and constitutes the dominant H$_2$O phase within their icy mantles. Here, we use deep learning and ab initio molecular dynamics to investigate the thermal and protonic transport properties of superionic H$_2$O ice. We demonstrate that superionic H$_2$O ice exhibits a pronounced protonic thermoelectric effect, with a maximum Seebeck coefficient that can reach $\sim 620$ $\mu$V K$^{-1}$ within the interior of Uranus, whereas Neptune's is lower, within the range of 570-585 $\mu$V K$^{-1}$. Consequently, the temperature gradients in the icy mantles can induce proton migration, thereby driving magnetic field generation. Based on this mechanism, and within a dipolar approximation that captures the mean field, the disparities in mean dipolar magnetic field strength between Uranus and Neptune can be explained exclusively by their differing internal temperature gradients, and the predicted mean field strengths are comparable to those observed by Voyager 2.

Stroboscopic measurements of a time-dependent projector generate a quantum Zeno dynamics whose effective Hamiltonian is the Kato-Avron Hamiltonian for parallel transport, which reduces to counterdiabatic driving in the case of a nonselective measurement of the instantaneous eigenprojectors of the system. The same generator arises under continuous monitoring of a time-dependent observable and under a time-varying complex absorbing potential. Departures from the ideal Zeno limit are governed, in all three settings, by a single positive leakage operator with a dynamical and a purely geometric contribution. Matching the corresponding generators yields a model-independent generalized Schulman relation for the quantum Zeno dynamics in the three scenarios, and a purely geometric bound on the measurement resources needed to steer a subspace along a prescribed path.

Cities are often compared through scaling laws, usually expressed as power-law relations between population size and aggregate urban quantities related to infrastructure, socioeconomic activity, or environmental impacts. These laws are influential because their exponent is often interpreted as describing what happens when a city grows, with implications for urban theory, planning, and policy. Here, we show that this interpretation is generally misleading. An exponent measured by comparing many cities at one date does not, in general, describe the trajectory of any individual city. Instead, it reflects a statistical pattern produced by cities with different histories, constraints, institutions, and growth paths. Apparent sublinear or superlinear scaling can therefore arise even when individual cities follow simpler dynamics, as we show for the area--population relation. Cross-sectional scaling laws can reveal system-level regularities, but should not be used alone to infer growth mechanisms or guide policy for a given city.

We establish a rigorous operator-space condition for the thermalization of typical initial states. We introduce a concept of simple slow operators (SSOs), defined as operators that evolve slowly under Heisenberg-picture dynamics and have significant small-sized components. We show that the non-thermalization of typical initial states drawn from a weakly entangled state ensemble implies the existence of SSOs; equivalently, the absence of SSOs implies that typical initial states thermalize. We establish these results by introducing the concept of an ensemble variance norm of an operator, defined as the typical magnitude of the expectation value of that operator with respect to states in the ensemble. For low-entanglement ensembles, the norm is related to operator sizes, allowing us to establish a direct link between operator dynamics and thermalization.

Boundary time crystals (BTCs) are paradigmatic examples of continuous time crystals that emerge in collective, dissipative quantum systems. Their microscopic origin, however, remains obscured by the complexity of Lindbladian many-body dynamics and has largely been investigated through semiclassical and numerical approaches. Here, we develop an exact operator space framework for collective spin Lindbladians based on irreducible tensor representations. We map the Lindbladian dynamics onto a local non-Hermitian hopping problem, where weak symmetries impose selection rules on operator transport, while the hopping amplitudes and their relative strengths determine the resulting dynamical regimes. We identify the microscopic ingredients that distinguish models supporting conventional collective precession from those supporting BTC dynamics. Our approach further reveals how non-unital dissipation can provide a source for the traceless operator subspace, providing a microscopic mechanism for the reduced sensitivity of BTC dynamics to initial conditions beyond mean-field descriptions. More broadly, our results establish operator space transport as a general perspective for understanding dissipative many-body dynamics and its connections to non-Hermitian phenomena.

Interpretable machine learning techniques are becoming essential tools for extracting physical insights from complex quantum data. We build on recent advances in variational autoencoders to demonstrate that such models can learn physically meaningful and interpretable representations from a broad class of unlabeled quantum datasets. From raw measurement data alone, the learned representation reveals rich information about the underlying structure of quantum phase diagrams. We further augment the learning pipeline with symbolic methods, enabling the discovery of compact analytical descriptors that serve as order parameters for the distinct regimes emerging in the learned representations. We demonstrate the framework on experimental Rydberg-atom snapshots, classical shadows of the cluster Ising model, and hybrid discrete-continuous fermionic data, revealing previously unreported phenomena such as a corner-ordering pattern in the Rydberg arrays. These results establish a general framework, which constitutes an important step toward the autonomous discovery of physical descriptors from diverse quantum datasets. All methods are available through qdisc, an open-source Python library designed to make these tools accessible to the broader community.

The Korteweg-De Vries (KdV) equation is a paradigmatic model of integrable classical fields, with solitonic solutions where localised profiles interact by elastic, factorised scattering. When solitons interact, their shapes are modified, and individual solitons cannot be identified. This is a key problem in soliton gas where one needs a density of solitons per unit distance: can we locate asymptotic objects, quasiparticles, even at finite times in the macroscopic limit? Quasiparticles' positions should satisfy locality properties, the field in mesoscopic regions being determined by quasiparticles lying there. We solve this problem for the KdV equation. We define solitons' positions as functions of spectral and impact parameters via an expansion bijection generalising that of hard rods. These ``KdV rods'' solve the semiclassical Bethe equations, implementing the collision rate ansatz, and satisfy a repulsion condition generalising the rods' lengths to the KdV scattering shifts and related to the condensate condition. This gives an explicit characterisation of multi-soliton fields in terms of solitons' positions instead of impact parameters. We construct fluid-cell projections, that project out solitons lying outside mesoscopic regions: the resulting field is unchanged in this region and supported there up to small corrections. We show that in the weak limit, conserved densities are given by the empirical density for these solitons' positions. Thus we have associated a kinetic theory of quasiparticles to the KdV equation. The results hold under natural assumptions on spectral and impact parameters, and no randomness is required. Our proof is based on novel solitonic tau functions. This is a crucial step towards rigorously deriving the kinetic equation of the KdV soliton gas, first proposed by Gennady El in 2003. We believe the methods are generalisable to other solitonic models.

Chain-of-thought (CoT) reasoning has become a widely used mechanism for eliciting multi-step reasoning in large language models by generating intermediate reasoning steps at inference time. Yet the scaling behavior of generalization with CoT depth remains poorly understood. To address this question, we study a theoretically solvable model of CoT for in-context weight prediction in linear regression, where test-time reasoning is represented as an iterative refinement of the weight-parameter estimate. Using tools from random matrix theory under high-dimensional asymptotics, we derive an exact formula for the generalization error as a function of reasoning depth, pretraining data amount, and context length. Our analysis reveals a sharp phase transition separating exponential and polynomial improvement, saturation, and overthinking, and characterizes how the optimal reasoning depth scales. We further show that deeper reasoning is most effective with sufficiently rich pretraining and in-context information, whereas limited pretraining or context makes longer reasoning prone to error amplification or saturation. We also validate these predictions through experiments on fully learned linear attention and softmax attention models. Our results provide a unified theoretical account of how test-time CoT depth affects generalization.

When stochastic field dynamics are cast into a path-integral formulation, perturbation theory becomes systematic but the resulting expansion quickly grows combinatorially large. The setting targeted here includes fields with several components and several dimensions, matrix propagators, tensor-valued couplings, and non-Gaussian driving noise specified by arbitrary n-point cumulants. Wick pairings grow factorially, and component indices must be routed through the tensor-valued vertices. The useful output is not a raw contraction list, but a diagram table: one entry per topology, with multiplicities, coupling sums, signs, and causal constraints resolved. We present sft-wick, an open-source Python package that constructs these diagram tables and computes their integrals numerically. Given an action and an observable, it enumerates topologically distinct Feynman diagrams, derives their algebraic coefficients, and evaluates the resulting diagram integrals from user-supplied response and cumulant functions. The core algorithm enumerates spatial topologies before routing component indices, avoiding contraction-by-contraction Wick expansion. Response-field constraints, including vanishing response-response contractions, the Ito prescription, and the absence of causal response loops, are enforced during enumeration. Predictions are validated against direct Langevin simulations in two worked examples, with Gaussian and with non-Gaussian driving noise, and agree with the simulations within stated error budgets.

We present a systematic study of finite, non-split 2-group symmetries with a non-trivial Postnikov class, focusing on the simplest example with a $\mathbb{Z}_2$ 0-form symmetry and a $\mathbb{Z}_2$ 1-form symmetry, intertwined together by the non-trivial Postnikov class in $H^3(B\mathbb{Z}_2;\mathbb{Z}_2)\cong\mathbb{Z}_2$, denoted by $\mathcal{G}$. We classify the anomalies of this 2-group symmetry for physical theories in $d$-dimensional spacetime, by computing the oriented bordism groups $\Omega_{d+1}^{\rm SO}(B\mathcal{G})$ and the spin bordism groups $\Omega_{d+1}^{\rm Spin}(B\mathcal{G})$ for $d\leq 5$. For the case of $d=3$, we investigate the Symmetry TFT/TO of the 2-group symmetry $\mathcal{G}$ using the language of fusion 2-categories, as well as (3+1)D TQFT actions, for the cases without or with the 2-group anomaly classified by $\operatorname{Hom}\left(\widetilde{\Omega}_4^{\rm SO}(B\mathcal{G}),U(1)\right) \cong H^4(B\mathcal{G};U(1))\cong\mathbb{Z}_2$. We classify the minimal topological and physical boundary conditions of the Symmetry TFTs, and carry out the categorical Landau paradigm for such a non-split finite 2-group.

Nonequilibrium statistical mechanics is the science of time as it manifests itself in the transient or steady entropy producing dynamical condition of many-body systems. Beyond the vivid multiformity of the phenomena themselves, three foundational issues lie at its heart. The first question concerns the very origin of entropy production, which gives macroscopic processes their direction and thereby defines the arrow of time: how does an atomistic mechanical world give rise to dissipated heat, thermalization, and time-reversal symmetry breaking? The second asks why, far beyond the familiar behavior of equilibrium systems, driving or agitation may produce and select stable and functionally rich structures: what is it about far-from-equilibrium, low-entropy driving that unleashes the wealth and intricacy of the natural world? The third issue is partly methodological: to determine how, and for which subclass of such wildly diverse nonequilibrium systems, a systematic, unified description and modeling from first principles remains possible. This essay addresses these issues in an informal, semi-popular-science style, offering a personally engaging yet wide-ranging introduction to the complementary roles of entropy production and the less familiar, more recently coined notion of frenesy in the dynamical fluctuations of steadily driven systems. Together, we argue, they provide a more complete starting point for understanding physical time on mesoscopic to macroscopic scales.