Papers

Separating homogeneous and inhomogeneous contributions to a spectral linewidth is essential for connecting optical spectra to microscopic dephasing and disorder. We quantitatively compare linewidth separation by one-dimensional Voigt analysis and two-dimensional coherent spectroscopy (2DCS). Using photoluminescence and 2DCS measurements of the same hBN-encapsulated monolayer MoSe2 sample, we construct uncertainty-weighted ḩi}^2 landscapes for the Gaussian inhomogeneous width and Lorentzian homogeneous half-width. Although a Voigt profile accurately reproduces the photoluminescence spectrum, the two widths are strongly anticorrelated and therefore poorly determined independently. By contrast, joint fitting of diagonal and cross-diagonal 2DCS slices produces more compact confidence regions with reduced parameter correlation and elongation. These results quantitatively demonstrate the improved linewidth separation provided by 2DCS and illustrate the limitations of assigning homogeneous and inhomogeneous contributions from one-dimensional Voigt fits alone.

Foundation machine learning force fields (MLFFs) such as MACE-MP-0 and UMA cover broad chemical space at near density functional theory (DFT) accuracy. However, they assume equilibrium ground-state physics and do not natively handle externally induced changes to the electronic state, such as charging, applied fields, or electronic excitation, which limits their use for driven processes such as photoexcitation and charge injection. We propose EquiFiLM, a lightweight extension that adds continuous external conditioning to any equivariant foundation MLFF via a per-layer Feature-wise Linear Modulation (FiLM) block, learning externally driven changes to the potential energy surface from minimal training data. The block modulates only scalar channels and preserves E(3)-equivariance exactly. We demonstrate the recipe on charged liquid water with the foundation model MACE-MatPES as the backbone, yielding E-MACE. On the four training charges, E-MACE delivers a $3.1\times$ reduction in force RMSE ($21.3$ to $6.96$ meV/$\mathring{A}$) and a $61\times$ reduction in per-atom energy RMSE ($6.1$ to $0.1$ meV/atom) over a baseline without EquiFiLM trained on the same data, at indistinguishable inference cost. Across seven held-out interpolation and extrapolation charges, force RMSE stays within $18-61$ meV/$\mathring{A}$ and energy RMSE within $0.7-5.4$ meV/atom. The model runs stable molecular dynamics across the full range tested and predicts the charge-dependent first-shell response of the reduced pair distribution function probed by ultrafast electron diffraction. Adding this conditioning axis to the foundation requires only a few thousand DFT-labeled frames, against the $\approx 10^8$ structures of a charge-aware foundation trained from scratch. The recipe is backbone- and conditioning-agnostic: it applies without architectural change to any equivariant MLFF with scalar interaction-layer channels.

Cobalt-doped Fe$_5$GeTe$_2$ possesses a rich magnetic phase diagram as a function of Co concentration. The nature of magnetic order in (Co$_{0.5}$Fe$_{0.5}$)$_5$GeTe$_2$ is especially interesting, as it has been shown to exhibit ferromagnetic order, A-type antiferromagnetic (AFM) order, or potentially both at the same time. Here we present magnetoresistance measurements on antiferromagnetic (Co$_{0.5}$Fe$_{0.5}$)$_5$GeTe$_2$ at a series of pressures and extract the anisotropy and interlayer exchange fields using the two-sublattice model. We show a 50 % increase of the interlayer exchange at 2 GPa, highlighting the sensitivity of magnetic properties to interlayer distance. In addition, we find that the sharp hysteretic transitions observed within the AFM state can be qualitatively described by a linear chain model, which suggests an even-odd effect as a function of layer number instead of a coexisting ferromagnetic phase.

In clean electron gases at low-to-moderate temperatures, odd-parity modes of the Fermi surface are anomalously long-lived due to Pauli blocking, giving rise to “tomographic transport” that is not captured by a hydrodynamic model. Here we show that tomographic flow in a Corbino disk induces an extended boundary layer near electrodes with superballistic transport and enhanced slip velocity, which leads to a parametric enhancement of the quadratic magnetoresistance coefficient. The enhancement depends explicitly on the electrode curvature, allowing its strength to be controlled by the device geometry. The magnetoresistance coefficient reveals three distinct regimes as a function of magnetic field: a tomographic regime at weak fields; a hydrodynamic regime at intermediate fields, reached when the cyclotron radius becomes comparable to a large odd-mode mean free path; and a conventional Ohmic regime at large fields, reached when the cyclotron radius becomes comparable to the short even-mode mean free path. The tomographic regime is characterized by an anomalous dependence of the magnetoresistance on temperature and density, which may account for recent experimentally observed anomalous scaling of the electron viscosity.

We study the multidimensional erratic structure of correlation functions produced by local operator quenches in finite-volume free massive scalar field theory in dimensions 2 and 3. The basic observable is the subtracted equal-time two-point function in the locally excited state and its spatiotemporal patterns of extrema. We analyze these extrema by the multidimensional diagnostics recently introduced for chaotic scattering amplitudes and related problems: all-pair distance distributions, nearest-neighbor spacings, greedy-path spacing ratios, and the extrema form factor. For the $1+1$-dimensional local quench we find that, in the regime of small Euclidean smearing, the fitted extremum statistics move close to the $\beta=1$ random-matrix benchmark, while increasing the smearing scale softens the effective repulsion and moves the distributions away from the GOE-like value. For the $2+1$-dimensional local quench we find that the nearest-neighbor statistics of the refined extrema are close to, or above, the $\beta=1$ benchmark, and the greedy-path ratio statistics are described by even larger effective $\beta$ values. Finally we studied the all-pair extrema spatial form factor and found that, in the one-, two-, and three-dimensional cases, its main structure is controlled by the corresponding uniform interval, rectangle, or cuboid geometry of the extrema cloud and found the dip-ram-plateau structure in the last two cases. Thus the form factor provides a complementary global diagnostic of how the extrema fill their effective metric support, while the genuinely nontrivial local and mesoscopic organization is carried by the nearest-neighbor and greedy-path statistics.

Level statistics in non-integrable quantum many-body systems with time reversal symmetry are expected to follow the Gaussian Orthogonal Ensemble (GOE), a hallmark of quantum chaos. However, we show that the interacting Su-Schrieffer-Heeger model exhibits a clear suppression of the mean level-spacing ratio $\langle r\rangle$ from the GOE value $\approx 0.535$, persisting deep in the nonintegrable regime. This challenges the conventional association between non-integrability and fully chaotic spectral statistics. Using exact diagonalization supported by semi-analytical arguments, we trace this anomaly to incomplete hybridization of many-body band states inherited from the noninteracting band structure. The resulting restructuring of the spectrum weakens level repulsion without restoring integrability. We show the robustness of this mechanism in extensions of the model which break chiral and inversion symmetry.

Within the tight binding framework of graphenes {\pi} electron nearest neighbors, the Tan Bo model parametrizes transition energies t(dr) based on bond lengths and angles via the Mobius transformation combined with exponential decay. Comparisons between isotropic , geometrically anisotropic , and Slater Koster scales reveal that B = 0 is equivalent to the SK scheme, with L(B) reaching its optimum at Bopt = 0. The Hermitian assembly maintains the Dirac cone at the K point.The Tan Bo geometry dependent transition model and non Hermitian TB assembly scheme developed in this study provide a reproducible single particle benchmark and parameterization reference for future non Hermitian chemical calculations incorporating electron correlation effects in graphene systems.

We develop a Hartree-Fock numerical method for computing the band structure of a two-dimensional Wigner crystal in an electron gas at zero temperature. The ground state is assumed to be fully spin-polarized. Single-particle excitation spectra are evaluated in spin-conserving channel. As an application, we use the developed code to compute the static dielectric function epsilon(q,0) of a Wigner-crystal state formed in a two-dimensional transition-metal dichalcogenide, specifically monolayer WSe2. The dielectric response is obtained from the Hartree-Fock band structure and eigenfunctions through a static Lindhard-type polarizability. The method provides a theoretical tool for investigating screening, band-structure reconstruction, and interaction effects in low-density two-dimensional systems, with possible relevance for future experimental studies.

Quantum photonic technologies greatly benefit from quantum light emitters with high brightness, indistinguishability, and reliable polarization characteristics. Achieving optimal performance relies on the accurate localization of emitters and their deterministic integration into tailored photonic structures with nanometer-scale accuracy. Although marker-based photoluminescence imaging techniques can achieve statistical fitting uncertainties below 10 nm, the ultimate integration yield is often limited by uncorrected systematic distortions in custom cryo-optical setups that compromise metrological accuracy. Here, we present an in situ calibration protocol that uses lithographically defined gold nanodisk arrays as references to calibrate optical distortions with a Zernike vector-field model. On held-out validation patterns beyond the calibration dataset, this correction reduces the residual systematic bias to 5.3 nm with a 2D scatter of 24.6 nm across the analyzed field of view. Furthermore, we demonstrate that applying this correction to the deterministic fabrication of circular mesa structures around semiconductor quantum dots reduces the variance in emission polarization by 49%, indicating improved registration accuracy. This calibration strategy offers a practical route to high-yield deterministic integration of quantum emitters into scalable quantum photonic circuits.

Characterizing a quantum state through the lens of quantum resources provides an information-theoretic perspective on many-body systems. While quantum entanglement serves as the paradigmatic example of a quantum resource, recent studies have shown that quantum magic, a resource for universal quantum computation, captures aspects of many-body states complementary to those described by entanglement. For instance, in spin systems, conformal field theory (CFT) analysis of the stabilizer Rényi entropy has revealed universal features of nonstabilizerness qualitatively distinct from entanglement. In bosonic and fermionic systems, however, a comparable formulation for their computational resource, non-Gaussianity, has yet to be established. In this work, we introduce a unified measure, the magic Rényi entropy (MRE), to quantify computational resources in spins, bosons, and fermions on an equal footing. We show that the MRE is a resource monotone under stabilizer and Gaussian protocols involving measurements and feedforward operations. The MRE reveals common universal aspects of nonstabilizerness and non-Gaussianity in critical many-body states. In particular, our CFT analysis shows that the universal contribution to the MRE appears as the size-independent term determined by the Affleck-Ludwig boundary entropy. We find that non-Gaussianity can continuously renormalize this universal contribution or drive a boundary transition through bulk-induced boundary renormalization-group flows. As a concrete example, we present a CFT analysis of non-Gaussianity in interacting spinless fermions described by the Tomonaga-Luttinger liquid, showing boundary transitions at the Luttinger parameters $K=1/3$ and $K=3$. Our field-theoretical predictions are confirmed by numerical calculations. These results provide a unified field-theoretical understanding of many-body magic across spins, bosons, and fermions.

We investigated the magnetotransport properties of single-crystals of tetragonal van der Waals compound EuNi$_2$As$_2$, that orders antiferromagnetically below 14.6 K in an incommensurate helical structure. Metamagnetic transitions are revealed by the magnetization measured in the magnetic field applied transverse to the axis of the helix, and are clearly reflected in the magnetoresistance. Overall, the magnetoresistance is small, but shows complex changes with the temperature, the strength, and the angle of the applied magnetic field. In magnetically ordered state, magnetoresistance shows prominent anomalies related to the metamagnetic transitions. For temperatures above the Néel point the negative magnetoresistance can be modeled very well with de Gennes-Friedel mechanism of the spin-disorder-scattering reduction. Hall resistivity data indicate hole-dominated multi-band conductivity in antiferromagnetic state and single-band one above the Néel temperature, with carrier concentrations of the order of 10$^{22}$cm$^{-3}$. This metallic character of the compound seems to obscure the plausible topological contribution to the Hall resistivity. Our ab-initio calculations of electronic band structure showed that the electronic structure changes very strongly upon magnetic ordering, but the density of states at the Fermi level differs by a factor smaller than two, in agreement with experimental Hall resistivity data. Meaningful changes in the density of states, magnetic moments, and screening length of Eu-4$f$ orbitals are discussed in terms of the effects of Hubbard corrections.

We report a fully analytical description of zero-temperature itinerant ferromagnetism in repulsive SU(N) Fermi gases with arbitrary mass imbalance among components. Using perturbation theory in the gas parameter x = kFa0, with kF the Fermi momentum and a0 the s-wave scattering length, we derive the second-order energy for arbitrary spin polarization and arbitrary mass ratio. Our main result is a closed analytic expression for the beyond-mean-field correction in mixtures with unequal masses. This analytical result extends the theory of dilute Fermi gases beyond the mass-balanced case and provides a compact equation of state for multicomponent mixtures. We show that mass imbalance breaks the paramagnetic symmetry already in the non-interacting limit, favors the occu pation of heavier components, and lowers the interaction strength required to reach a fully polarized state. For S = 1/2, the system evolves continuously from a mass-induced partially polarized state to full ferromagnetism. For larger spins, distinct mass distributions generate qualitatively differ ent polarization paths, including smooth and discontinuous sequences. Our results identify mass imbalance as a powerful control tool for magnetic ordering in ultracold Fermi mixtures.

Molecular passivation of surface defects is key to improving the optoelectronic performance of hybrid halide perovskite materials, but the underlying atomistic mechanisms are incompletely understood. While machine-learned interatomic potentials are now widely used to simulate complex molecular and crystalline systems, their application to experimentally-realistic scenarios - such as molecules coordinating to perovskite surfaces - is still far from trivial. Here, we describe a multistep training pipeline, resembling continuous fine-tuning used for large language models, to underpin atomistic modelling and computational experiments in this domain. Our protocol involves two components: (i) a large, curated, and open dataset of diverse metal and hybrid halide perovskite structures ('hyP-26'); and (ii) a small, specialised dataset for an amino-silane molecule passivating the surface, providing highly specific information for fine-tuning. We apply this approach to explore collective behaviour at a mixed-composition halide perovskite surface passivated with a varying coverage of amino-silane molecules, revealing an evolution of interactions with increasing molecular surface coverage.

High-electron-mobility transistors (HEMTs) made with III-nitride materials are of potential use in high-temperature electronic applications including power electronics, communications, aerospace and space exploration. However, the demands of such applications make it essential to understand the thermal limits and performance evolution of III-nitride HEMTs. Here, we analyze the high-temperature operation of III-nitride HEMTs, examining the impact on material properties, device structure, and circuit-level behavior. We explore the role of critical device layers - including barrier and channel engineering, substrate selection, and passivation strategies - in mitigating high-temperature-induced effects, and evaluate the thermal stability of III-nitride HEMTs in logic, radiofrequency, and power electronics applications. We also highlight key remaining challenges in the design and optimization of III-nitride devices for high-temperature applications.

We introduce the notion of an Ising emulator for two-dimensional Ising models: a broad class of flat, unit-edge-length lattices can be represented as site- or bond-diluted supercells of a single host lattice, for which the Feynman–Vdovichenko/Kac–Ward solution is fixed once and for all. We construct explicit square and triangular emulators and show that a single transition matrix, supplemented by lattice-specific binary masks, gives all the thermodynamic quantities of interest for both ferro- and antiferromagnetic couplings. We apply the framework to all eleven Archimedean lattices, to all twenty 2-uniform lattices – whose thermodynamics is obtained here for the first time – and to several pentagonal lattices, and show that the same construction extends directly to fractal and disordered Ising models, with no modification to the underlying machinery.

At equilibrium, the ratio of two steady-state probabilities is a Boltzmann factor, set by a free-energy difference. Such ratios are the natural, normalization-independent readouts of both thermodynamics and information processing, and are often used as a measure of fidelity in biophysical systems. What becomes of these ratios once a system is driven from equilibrium, where the Boltzmann factor no longer holds? Representing Markov processes as graphs and their steady states as averages over a distribution on spanning trees, the arboreal distribution, we track the ratio $\pi_i/\pi_j$ under driving along energetic edges, where detailed balance is broken, relative to its equilibrium value. Our central finding is that a chosen ratio can stay exactly locked to its equilibrium value arbitrarily far from equilibrium, a phenomenon we call energetic protection, whenever an algebraic equality between spanning-tree weights holds. Just as detailed balance constrains rates around cycles, energetic protection constrains weights across trees, providing a new mechanism for robustness against fluctuations in the driving force, such as variations in ATP concentration. Away from this equality, single-edge driving collapses the response onto two arboreal coefficients and forces it to be monotonic, so nonmonotonic single-edge control is impossible at any strength. With two energetic edges, protection and monotonicity combine into a thermodynamic switch that holds a function at its equilibrium value for as long as desired and releases it sharply. Equilibrium is known for the limits it places on information processing. We show that new constraints, both no-go principles and exact invariances, survive far from equilibrium. These results reveal how the localization of energy expenditure governs the functional logic of nonequilibrium systems in physics and biology.

Grain-refined metals typically exhibit high strength, yet their engineering applications are often constrained by grain coarsening under thermo-mechanical loading. Recent experiments have revealed abnormal grain growth (AGG) in ultrafine-grained Ni thin films subjected to cyclic loading at room temperature. Unlike conventional AGG, which generally requires significant plastic deformation or high temperatures, this phenomenon occurs within the regime of macroscopic elastic deformation. This AGG is characterized by the preferential growth of grains with an in-plane <100> orientation aligned with the loading direction. Here, we investigate the underlying physical mechanisms by combining phase-field simulations with micromechanical analysis. The results indicate that elastic energy reduction provides a thermodynamically plausible driving force for this orientation-selective grain growth. Phase-field simulations reveal the evolution kinetics of AGG and confirm that local grain geometry and stress states play critical roles in determining the grain growth pathway. By applying this framework to systems with varying elastic anisotropy, we establish a general approach for investigating elastically driven AGG in polycrystalline materials.

Phonon scattering selection rules are known to control heat flow through bulk solids. Here we show that these selection rules also modulate heat flow through nanoscale semiconductor films, although through a previously-unexplored mechanism. Using first-principles calculations, we expose a competition between these selection rules and phonon mode conversion at boundaries of nanoscale films, that drives mode-polarized heat currents at cryogenic temperatures ($\le$ 100 K). This polarizing effect is stronger in materials like indium phosphide, where selection rules based on large velocity differences between phonon branches amplifies the longitudinal acoustic (LA) phonon contribution to thermal conductivity by restricting their intrinsic scattering events, while boundary mode conversion in nanoscale films suppresses it by depopulating the LA phonons. The resulting transverse-polarized non-equilibrium phonons will enable symmetry-selective engineering of phonon coupling to electrons, strains and defects in nanoscale films, that is difficult to achieve in bulk solids.

NaRuO$_2$ forms a delafossite-like structure that contains triangular sublattices of edge-sharing RuO$_6$ octahedra. It shows no evidence of magnetic order down to 100 mK and persistent spin fluctuations, suggestive of a quantum disordered magnetic ground state. In order to characterize the physical regime from which this disordered state arises, we use resonant inelastic X-ray scattering (RIXS) and X-ray absorption spectroscopy (XAS) at the Ru-$L_{2,3}$-edge, along with pulsed high-field magnetization to characterize both the local electronic structure and the magnetic interactions. Despite significant spin-orbit coupling inferred from XAS measurements, a spin-orbit exciton, characteristic of a spin-orbit assisted Mott insulator, was not observed with RIXS due to the presence of damped intraorbital excitations, which are characteristic of a metal. Corroborated by models of the high-field magnetization to a random singlet model, we propose a picture of a nearly itinerant system with strong magnetic and charge fluctuations that destabilize long-range magnetic order.

We formulate the matrix product state (MPS) tangent-space excitation construction for finite, non-uniform systems with open boundary conditions, using the smooth full-rank stratum of the MPS variety as the variational manifold. The resulting linear tangent ansatz yields a projected-Hamiltonian eigenproblem for approximating excitation spectra. We further introduce a rank tomography that characterizes the particle-sector expressivity of the MPS tangent space. For number-conserving systems, we resolve the Schmidt ranks of reference states by particle number and derive an explicit relation between the resulting rank profile and the dimensions of the tangent-space sectors. This allows sector completeness and parametric deficiency to be determined directly from the reference state, without explicitly constructing a tangent basis, and provides a direct diagnostic of the sectorwise expressivity of the MPS excitation ansatz. We benchmark the finite-system construction on Bose–Hubbard chains against exact diagonalization, finding accurate low-lying excitation branches while identifying sector-dependent limitations of the linear tangent ansatz.

Molecular crystals are a highly polymorphic class of materials, with a single molecule commonly crystallizing via multiple packing patterns, making structure and property prediction very challenging. Crystal structure prediction typically comprises the production of sets of promising candidate structures, each considered in isolation rather than as samples in a thermodynamic distribution. Likewise, modern generative approaches to this problem, despite naturally sampling distributions of crystals, lack a concrete formulation of the distributions being sampled. Two components are required to impart meaning to the distributions of crystals generated under such models: a canonical parameterization, and a loss function which equilibrates the generated samples to some target distribution. We develop such a parameterization, and train energy-based generative flow networks (GFlowNets) to approximate the Boltzmann distribution over crystal structures for target molecules and space groups. Combined, these components comprise our MXtalGFlow framework for molecular crystal modeling. Going beyond sampling disconnected sets of low-energy structures, MXtalGFlow yields a thermodynamic distribution over crystal structures. We sample and analyze distributions of crystals for two molecules, each under two energy functions, a Lennard-Jones potential and the Universal Model for Atoms. We characterize the local structural basins about the known polymorphs, and identify additional as-yet un-reported packing modes with competitive probabilities to the known experimental structures. With MXtalGFlow, we illustrate how to define and train a model to sample a thermodynamically meaningful distribution of molecular crystals, and analyze such a distribution to glean useful information.

Aggregation and fragmentation processes are widespread in engineering and the natural world. Here, we investigate a distinct colloidal aggregation mechanism in an active system of motile bacteria in highly anisotropic environments. Specifically, we examine Escherichia coli bacteria swimming in one-dimensional confinement within nematic liquid crystals and observe long-lived chains of bacteria swimming along the nematic director. Crucially, we find that longer chains swim faster, in apparent contradiction to fundamental force-balance models that predict the swimming speed to be independent of chain length, as chains should swim at the average speed of their individual components. The seeming discrepancy is resolved by recognizing that chains do not form randomly but self-organize due to the relative velocities between bacteria. To elucidate the physical mechanism behind this active aggregation process, we combine our experimental findings with a minimal model of nearest-neighbour aggregation and agent-based simulations of active particles aggregating in one dimension. Consistent with experimental observations, our agent-based simulations reveal a positive correlation between the length and speed of dynamically self-assembled chains of active particles, with the correlation depending on the variance of the individual speed distribution and diminishing over time. Together, our experiments and theoretical models indicate a distinct regime of swimming-limited aggregation whose evolution is constrained by the intrinsic speed distribution of active agents, providing new insight into bacterial self-organization.

Classical nucleation theory (CNT) describes the formation of a stable phase from a metastable one in terms of a single reaction coordinate that corresponds to the radius of a nucleating droplet. In this work, we provide a full account of nonequilibrium nucleation theory (NNT), which generalizes CNT to non-equilibrium field theories with non-conserved order parameter. We present two equivalent derivations of the dynamics of the droplet radius: a stochastic route, based on a direct projection of the stochastic field equation onto the radial reaction coordinate, and a route based on the minimization of the Freidlin-Wentzell action. Crucially, the quasipotential barrier predicted by NNT differs from the one found when assuming the instanton to be the time-reversal of the relaxation dynamics. Whereas the interfacial density profile differs from that on the relaxation path, an analytical derivation of NNT remains possible using a careful definition of the reaction coordinate. This leverages the perturbative structure that (in common with CNT) emerges in the limit of large critical radius. We further derive with similar techniques the dynamics of capillary waves, whose stability is required for the CNT/NNT precept of a near-spherical droplet to prevail. After deriving our theory for generic non-conserved field-theories, we address two explicit examples: a non-equilibrium generalization of Model A (Active Model A), and a population dynamics model (with two choices of noise that each break time-reversal symmetry). In both cases, we validate our analytical NNT against numerical results obtained by action minimization, with excellent agreement. NNT provide a systematic framework for constructing nucleation theories in a broad class of non-equilibrium systems from active matter, reaction-diffusion systems and population dynamics.

Quantum matter emerges from the interplay of fluctuations, topology, and entanglement, which - in equilibrium - governs quantized transport, universal criticality, and topological classification. Non-Hermitian systems, widely explored in platforms ranging from electric circuits to photonics, are intrinsically out-of-equilibrium, and display fundamentally new phenomena, including complex spectra, spectral winding, exceptional topology, and non-unitary dynamics. A central challenge is understanding how the complex single-particle spectrum governs universal many-body behavior. We introduce a symmetry-protected dynamical topological index derived directly from the complex spectrum. Through the lens of algebraic topology, more specifically Morse theory, we identify critical points in the spectrum with topological defects, whose curvature and stability are protected under continuous deformations. This links spectral geometry to many-body observables, unifying non-Hermitian band topology, entanglement, and transport. We demonstrate that non-Hermitian quantum criticality in non-interacting systems is controlled by gain-and-loss-selected non-equilibrium steady states, which dynamically generate an emergent imaginary Fermi surface whose Fermi points host scale-invariant gapless modes with logarithmic entanglement scaling and algebraic correlations. Our work establishes a unified framework for non-Hermitian quantum matter, connecting spectral topology to Morse theory, revealing a topological foundation of non-equilibrium quantum criticality.

In variational Monte Carlo (VMC) calculations of $N$-site quantum systems with arbitrary all-to-all two-body interactions, evaluating the local energy generally costs $O(N^3)$. We introduce a new framework that reduces this cost to $O(N)$ for tensor network states, capable of scalable and accurate computation of real-time dynamics and ground states. As a result, we obtain accurate simulations of the adiabatic real-time protocol of a $10\times10$ dipolar XY model realized in a Rydberg simulator [C. Chen et al., Nature 616, 691 (2023)], which was previously beyond the reach of classical simulation. Going beyond quantum experiments, we also directly perform ground state VMC to compare with the adiabatic state preparation. Our work demonstrates tensor network VMC as a powerful classical simulator for long-range quantum platforms such as Rydberg and ion-trap simulators, which are currently in urgent need of scalable classical benchmarking tools. As a separate technical contribution, we resolve the pathology of evolving from product states within of tensor network VMC.

We study a Brownian particle in a harmonic trap whose stiffness switches between two values with arbitrary waiting-time statistics, generating semi-Markovian dynamics. To treat the resulting temporal memory, we formulate the problem in an enlarged age-structured state space, restoring Markovianity and yielding a local Fokker–Planck description. Within this framework, we derive exact steady-state integral equations for the spatial and birth distributions and obtain exact expressions for stationary moments, injected power, and potential energy. In the second part of the paper, we analyze the stochastic-resetting limit, corresponding to a particle alternately released and trapped. By representing the stationary spatial distribution as a superposition of Gaussian states with fluctuating variance, the problem can be reformulated as a switching process in variance space. This yields exact integral equations for the variance distributions and leads to a simplified description amenable to direct analytical treatment.

Metal-semiconductor junctions in optoelectronic devices are commonly engineered to promote charge separation. In Pt/TiO2 Schottky junctions, Pt is typically regarded as a catalytic electron sink rather than a visible-light-active component. Here, we demonstrate that Pt nanoislands on TiO2 can generate photochemically active carriers under visible light excitation. Using quantitative scanning photoelectrochemical microscopy, we measure the wavelength-resolved external quantum efficiency (EQE) of Au and Pt nanoisland arrays on TiO2, and correlate their reactivity with their morphology and extinction spectra. Discrete 10 nm Pt nanoislands exhibit robust broadband visible light photoactivity - exceeding the photoactivity of similar-sized Au nanoislands under blue-green excitation - whereas Pt's photoactivity is strongly suppressed when the nanoislands are connected. Surprisingly, Pt exhibits an EQE-per-atom approx. 20 times higher than Au at 455 nm and approx. 2 times higher at 595 nm (at Au's optimum). We show an approximately wavelength-independent Pt internal quantum efficiency of approx. 1 percent across the visible spectral region. These findings reposition catalytic metals with strongly damped optical response in the visible as light-responsive components in metal-semiconductor hybrids, challenging the prevailing perception that they function solely as passive co-catalysts in photocatalytic systems.

Ising machines are heuristic solvers for combinatorial optimization, but their solution quality can degrade when large-scale constrained problems are solved directly. Ising-machine-assisted large neighborhood search (LNS) instead repeatedly updates a feasible current solution by solving smaller subproblems. An existing feasibility-preserving method for the vehicle routing problem (VRP) re-optimizes the entire routes of selected vehicles and thus cannot adjust the subproblem size finely. We propose LNS-VT, which introduces the number of consecutive steps re-optimized per vehicle as a parameter to control the subproblem size finely while preserving feasibility. For a 300-site, 5-vehicle VRP, its best setting reduced the objective value by approximately 10% relative to the existing method after 100 iterations, and the appropriate setting changed with the current solution quality. Applying the same principle to the quadratic multiple knapsack problem, we confirmed that an appropriate subproblem size also exists, indicating that subproblem-size control is important in Ising-machine-assisted LNS.

We propose a numerical algorithm to construct a Markov model with an extended list of variables to parameterize the equation of motion of a multidimensional coarse-grained physical system in an external potential, when memory effects are relevant. Our method uses autocorrelation data of the stationary velocities, but it avoids the inverse problem of finding the corresponding memory kernel from these data in a first step. Rather, the data are used to construct a Prony series approximation of the autocorrelation function, and the parameters of this Prony series provide the corresponding Markov model. Numerical results for molecular dynamics data show a good match for parameterized models with five auxiliary variables for a one-dimensional, and twelve auxiliary variables for a two-dimensional system.

We extend the coadjoint orbit approach to bosonization systematized by Delacretaz-Du-Mehta-Son to double-scaled non-relativistic Fermi liquids with central inverted harmonic oscillator potential. In 1+1d, this reproduces the Das-Jevicki collective field theory describing quasiparticle excitations of the $c=1$ matrix model. In 2+1d, this yields an effective field theory for noncritical M-theory, namely the 2+1d Fermi liquid proposed by Hořava and Keeler as a unified framework for characterizing noncritical string vacua. With a suitable gauge choice this theory reduces to a continuous family of 1+1d chiral bosons resembling Das-Jevicki collective fields coupled by additional interactions. Utilizing the underlying integrability of noncritical M-theory, we compute select fermion density correlation functions order-by-order in perturbation theory, and provide evidence that they agree with their Fermi liquid counterparts in a suitable semiclassical limit. This represents a step toward an effective spacetime gravity description of noncritical M-theory, which we expect to shed light on both the landscape of 2d noncritical strings and 3d quantum gravity in general.