Soft Condensed Matter · Cross-listed from physics.bio-ph
Biology and Physics
Stuart A. Newman and Sahotra Sarkar
This article frames the relation between biology and physics by characterizing the former as a subdiscipline rather than a special case of the latter. To do this, we posit biological physics as the science of living matter in contrast to classic biophysics, the study of organismal properties by physical techniques. At the scale of the individual
cell, living matter is nonunitary, i.e., not composed of aggregated subunits, and has features (e.g., intracellular organizational arrangements and biomolecular condensates) that are unlike any materials of the nonliving world. In transiently or constitutively multicellular forms (social microorganisms, animals, plants), living matter sustains physical processes that are generic (shared with nonliving matter, e.g., subunit communication by molecular
diffusion in cellular slime molds), biogeneric (analogous to nonliving matter but realized through cellular activities, e.g., subunit demixing in animal embryos) or nongeneric (pertaining to sui generis materials, e.g., budding of active solids in plants). This "forms of matter" perspective is philosophically situated in the dialectical materialism of Engels and Hessen and the multilevel physicalism of Neurath and the logical empiricists. We counterpose this view to informationism and to genetic and other hierarchically reductionist physical theories of biological systems and highlight open questions regarding incompletely characterized and enigmatic forms of living matter.
Read the full abstract ▾
Soft Condensed Matter
Statistical Mechanics of Density- and Temperature-Dependent Potentials: Application to Condensed Phases within GenDPDE
Giuseppe Colella, Allan D. Mackie, James P. Larentzos et al. (+2 more)
Coarse-grain Lagrangian methods, such as Dissipative Particle Dynamics ( Hoogerbrugge et al., EPL, 1992), are suitable for describing mesoscopic fluid systems that include thermal fluctuations. However, the realistic simulation of
liquids using these methods represents a longstanding problem. In this work, we develop a local thermodynamic (LTh) model for the description of condensed phases within the framework of the Generalized Dissipative Particle Dynamics with Energy Conservation (GenDPDE) method (Bonet Avalos et al., PCCP 2019). Such a model is appropriate for the analysis of
liquids, due to the explicit account of the thermal expansion coefficient and isothermal compressibility at the mesoscale. We demonstrate the accuracy of the LTh model by examining the thermodynamic properties of argon at both
liquid and supercritical conditions, through
equilibrium simulations performed around two key reference states (125.7 K, 85.31 MPa, 1419.7 kg/m3 for
liquid Ar, and 418.8 K, 85.31 MPa, 695.99 kg/m3 for supercritical Ar). Remarkably, we show that the model is also valid over a range of thermodynamic conditions near the reference states, allowing a correct description of the physics of systems with spatial variations in density and temperature. We further derive analytical expressions for the macroscopic pressure and energy equations of state based on the model parameters, discussing their validity and limitations. We demonstrate that, even at the mean-field level, accurately capturing local particle arrangements is essential for predicting macroscopic thermodynamic properties from mesoscopic data. We also assess the applicability of the HNC approximation in predicting the radial distribution function of the GenDPDE system, exploring its strengths and limitations. With the LTh model, GenDPDE offers a dependable and versatile tool for analysing condensed phases through coarse-grain techniques.
Read the full abstract ▾
All authors Giuseppe Colella, Allan D. Mackie, James P. Larentzos, Fernando Bresme, Josep Bonet Avalos
Statistical Mechanics
Pattern stability in reaction-diffusion systems depends on path entropy
Eric R. Heller and David T. Limmer
Reaction-
diffusion systems driven far from thermodynamic
equilibrium through the injection of energy can support multiple spatial patterns that persist as long-lived dynamical phases. The stability of these metastable phases is not determined by thermodynamics, but by the transition paths connecting them. At finite particle numbers, intrinsic stochasticity induces rare transitions between competing patterns, rendering continuum mean-field descriptions insufficient, while exact
stochastic simulations become computationally prohibitive in spatially extended systems. Here, we make absolute instanton rate calculations, including fluctuation and
symmetry prefactors, tractable for transitions between metastable patterns in large nonequilibrium reaction-
diffusion systems. Applied to a canonical Schlögl model and an experimentally motivated ATP-driven membrane kinase-phosphatase network, the resulting rates agree closely with reaction-
diffusion master-equation
benchmarks. We show that an effective path
entropy can qualitatively alter stability at finite particle numbers by selectively enhancing one switching direction. These results establish path
entropy as an organizing principle for finite-particle nonequilibrium pattern stability.
Read the full abstract ▾
Quantum Gases · Cross-listed from quant-ph
Exact quantum scars from kinetic frustration for cross-platform realizations
Zhuoli Ding, Ruben Verresen and Zoe Z. Yan
Quantum many-body scars are nonthermal states exhibiting persistent revivals in an otherwise ergodic, nonintegrable
quantum system. Here we leverage the phenomenon of kinetic frustration – the destructive interference of multiple
quantum paths – to create exact scars. The simplicity makes these models directly suitable for implementation on multiple existing
quantum simulation platforms. In particular, we show how frustrated hardcore
bosons in cold atom Bose-Hubbard simulators and polar molecule or Rydberg atom tweezer arrays have persistent oscillations whose lifetimes can be tuned with experimentally accessible parameters, like the Hubbard interaction or a Floquet drive. Second, we propose an experimentally realizable scar within a non-integrable
Fermi-Hubbard model where the frustration arises from the fermionic exchange statistics, which admits a one-to-one mapping with the bosonic model in the scar subspace. Finally, we introduce a practical heuristic based on the energy distribution of eigenstates for systematically predicting and optimizing
quantum many-body scar lifetimes. Their cross-platform realizability and long lifetimes make them well-suited for benchmarking coherence and exploring nonergodic dynamics in current and near-term
quantum devices.
Read the full abstract ▾
Disordered Systems and Neural Networks · Cross-listed from quant-ph
DysonNet: Constant-Time Local Updates for Neural Quantum States
Lucas Winter and Andreas Nunnenkamp
Neural
quantum states (NQS) provide a flexible variational framework for many-body wavefunctions, but suffer from high computational cost and limited interpretability. We introduce DysonNet, a broad class of NQS that couples strictly local nonlinearities through global linear layers. This structure is analogous to a truncated Dyson series which gives an intuitive interpretation of local wavefunction updates as scattering from static
impurities. By resumming the scattering series, single-
spin-flip updates can be computed in $\mathcal{O}(1)$ time, independent of system size, using an
algorithm we call ABACUS. Implementing DysonNet with the state-space model S4, we obtain up to $230\times$ speedups over
Vision-
Transformers for computing the local
estimator. This corresponds to an asymptotic $\mathcal{O}(N^2)$ improvement in training-time scaling, reaching $\mathcal{O}(N \log^2 N)$ total training complexity in area-law phases.
Benchmarks on the 1D long-range Ising model and frustrated $J_1$-$J_2$ chains show that DysonNet matches state-of-the-art NQS accuracy while removing the dominant local-update overhead. More broadly, our results suggest a route to scalable NQS architectures where physical interpretability directly enables computational efficiency.
Read the full abstract ▾
Mesoscale and Nanoscale Physics
Hall conductance in a weakly time-reversal invariant open system
Alexander Fagerlund, Christopher Ekman and Rodrigo Arouca
The
quantum Hall effect and the
quantum anomalous
Hall effect both require time-reversal invariance to be broken. We show that non-
equilibrium effects can cause
Hall physics to arise even when the system is weakly time-reversal symmetric and no
magnetic field is applied. In our model, this occurs due to a fermionic subsystem breaking time-reversal invariance even if the system as a whole does not. The
fermions receive a TRI-breaking self-energy, caused by interactions with bosonic degrees of freedom in the system and with an external reservoir. As a result, the
fermions develop a non-quantized
Hall conductance. We demonstrate that, unlike in the
equilibrium case, the presence of a mass term is insufficient for the
Hall conductance to appear, and wave-function renormalization effects have to be included.
Read the full abstract ▾
Mesoscale and Nanoscale Physics
Controlled localization of anyons in a graphene quantum Hall interferometer
Christina E. Henzinger, James R. Ehrets, Rikuto Fushio et al. (+9 more)
Exchange statistics are a fundamental principle of
quantum mechanics, dictating the
symmetry of identical particle wavefunctions and thereby enabling emergent phenomena of many-body
quantum states. The exchange-induced
unitary transformation of both abelian and non-abelian anyonic wavefunctions can be probed using electronic fractional
quantum Hall (FQH) interferometers, where quasiparticles propagating along the interfering FQH edge braid with those localized within the interferometer. Here, we add a gate-controlled dot/anti-dot in the center of a
bilayer graphene FQH interferometer cavity to tune the number of enclosed anyons. We observe hundreds of controlled phase slips in the diagonal conductance across the interferometer for both abelian and non-abelian states, consistent with discrete changes in the localized quasiparticle population. For abelian anyons, the observed phase slips agree with the theoretically expected value. At half filling, our results suggest the interfering edge carries charge $|e^*/e| = 1/2$ abelian excitations, whereas charge $|e^*/e| = 1/4$ putative non-abelian anyons remain localized in the interferometer cavity. Controlling the population of localized $e/4$ anyons in an interferometer marks a significant milestone towards observing their non-local exchange statistics and building a fault tolerant topological
qubit based on non-abelian anyon manipulation.
Read the full abstract ▾
All authors Christina E. Henzinger, James R. Ehrets, Rikuto Fushio, Junkai Dong, Thomas Werkmeister, Marie E. Wesson, Kenji Watanabe, Takashi Taniguchi, Ashvin Vishwanath, Bertrand I. Halperin, Amir Yacoby, Philip Kim
Strongly Correlated Electrons
Can electronic quantum criticality drive phonon-induced linear-in-temperature resistivity?
Haoyu Guo and Debanjan Chowdhury
Optical
phonons naturally generate linear-in-$T$ resistivity in the high-temperature equipartition regime, but their finite gap prevents this mechanism from surviving to asymptotically low temperatures. Here we analyze whether proximity to an electronic
quantum critical point can remove this obstruction by strongly softening an optical
phonon. We first derive a model-independent criterion for such softened
phonons to control low-temperature transport: besides reducing the renormalized optical gap, the Landau-damped
phonon must acquire a dynamical exponent $z_p>d$, where $d$ is the spatial dimension of the
phonon, so that a sufficiently large thermally occupied phase space survives as $T\to 0$. We then analyze a concrete mechanism in which the
phonon couples nonlinearly to long-wavelength electronic collective modes near a $\vec{Q}=0$
quantum critical point, and apply it to the Ising-nematic case. Within a large-$N$ field theoretic formulation, the
phonon softening is enhanced near criticality, but in the clean theory the resulting dynamics lies at or near the marginal boundary for asymptotic $T$-linear scattering. Including feedback from the softened
phonon back onto the electronic critical sector further weakens the tendency toward robust low-temperature $T$-linear transport. Our results sharpen both the promise and the limitations of
phonon-based explanations of strange-metal transport near electronic criticality.
Read the full abstract ▾
Mesoscale and Nanoscale Physics
Imaging flat band electron hydrodynamics in biased bilayer graphene
Canxun Zhang, Evgeny Redekop, Hari Stoyanov et al. (+12 more)
Hydrodynamic electron transport arises when carrier kinetics are dominated by interelectron collisions rather than the relaxation of momentum out of the electron system. In recent years, signatures of electron hydrodynamics have been reported in
graphene devices owing to the low disorder and weak electron-
phonon coupling. However, these experiments have been performed in regimes where the carrier mass is light, and the electron-electron collision length–though smaller than corresponding lengths for
phonon or
impurity scattering–remains large in absolute terms, typically several hundred nanometers. This restricts hydrodynamic transport phenomena to large length scales, limiting miniaturization of devices based on hydrodynamic flow. The advent of dual-gated rhombohedral
graphene multilayers introduces a new route toward enhanced hydrodynamic behavior via their large–and tunable–effective mass. Here, we employ a scanning superconducting
magnetic sensor to image local current flow in dual-gated
bilayer graphene. Exploiting a sample geometry sensitive to both laminar and vortical flow, we identify three distinct transport regimes–ballistic, hydrodynamic, and diffusive–across the full phase space spanned by carrier density and displacement field. The strongest hydrodynamic transport is observed in the flat band regime, where fitting our results to a unified Boltzmann transport model reveals the electron-electron scattering length to be comparable to the
Fermi wavelength of ~50 nm. High-current measurements, meanwhile, reveal striking nonlinearities in the flow pattern. Our results pave the way for miniaturized electronic devices based on linear and nonlinear electron hydrodynamics.
Read the full abstract ▾
All authors Canxun Zhang, Evgeny Redekop, Hari Stoyanov, Jack H. Farrell, Sunghoon Kim, Ludwig Holleis, David Gong, Aidan Keough, Youngjoon Choi, Takashi Taniguchi, Kenji Watanabe, Martin E. Huber, Ania C. Bleszynski Jayich, Andrew Lucas, Andrea F. Young
Statistical Mechanics · Cross-listed from nlin.SI
Bootstrapping Fermionic $R$-operators with Decorated Yang–Baxter Equations
Zhao Zhang
Integrating infinitesimal generators of local dynamics into finite-time
evolution is generally harder than extracting a local
Hamiltonian from a
quantum gate. For integrable one-dimensional
quantum many-body systems, a recent bootstrap constructs one-parameter $R$-operators directly from
Hamiltonians satisfying the Reshetikhin condition. However, this condition excludes important models such as the Hubbard model, whose two-parameter $R$-operator was obtained by Shastry from a decorated Yang–Baxter equation obeyed by its free-
fermion sector. Here, I extend the bootstrap to $R$-operators constrained by both the ordinary and decorated Yang–Baxter equations. Their joint expansion produces additional
Hamiltonian-level necessary conditions and recursively determines candidate higher-order terms, subject to two-site locality at each order. I also derive compatibility and factorization conditions under which a Shastry-type superposition solves the $RLL$ relation after deformation by an onsite involution. The construction recovers the known two-parameter $R$-operators of the Hubbard and XYh models, whose full Yang–Baxter equations follow from established tetrahedral Zamolodchikov
algebra relations. For a superconducting Hubbard deformation, the scalar equations are generically incompatible, placing it outside this framework. These results provide diagnostics and a systematic route to fermionic $R$-operators beyond the Reshetikhin condition. General sufficiency, convergence of the formal bootstrap, and sufficiency of the deformation conditions remain open.
Read the full abstract ▾
Mesoscale and Nanoscale Physics
Selective braiding of different anyons in the even-denominator fractional quantum Hall effect
Jehyun Kim, Amit Shaer, Ravi Kumar et al. (+6 more)
Even-denominator
quantum Hall states can host several types of anyons with distinct exchange statistics. Depending on the anyon type, exchanging two quasiparticles can impart a phase to the many-body wave function or even transform it into a different state. Here, we realize a gate-tunable Fabry-Pérot interferometer with an embedded antidot that provides local control over the number of anyons within the interference loop. By independently tuning the
magnetic field, carrier densities across the device, and the antidot potential, we access regimes in which localized anyons form reproducibly and measure the associated statistical phases $e^{i \theta_\mathrm{braid}}$. We resolve braiding phases of $\theta_{\mathrm{braid}}=\pi$ and $\theta_{\mathrm{braid}}=\frac{\pi}{2}$, which we attribute to $e/2$ quasiparticles encircling either $e/2$ or $e/4$ quasiparticles, respectively. We further observe switching between different anyon occupancies of the antidot over time, directly resolving individual anyon tunnelling events into the interference loop. Similar behavior occurs at filling factor one third. Our work addresses one of the two key challenges in observing non-Abelian braiding, which requires control of both localized and interfering anyon types.
Read the full abstract ▾
All authors Jehyun Kim, Amit Shaer, Ravi Kumar, Alexey Ilin, Kenji Watanabe, Takashi Taniguchi, Ady Stern, David F. Mross, Yuval Ronen
Disordered Systems and Neural Networks · Cross-listed from cs.LG
Algorithmic Task Capture, Computational Complexity, and Inductive Bias of Infinite Transformers
Orit Davidovich and Zohar Ringel
We formally define algorithmic capture of combinatorial tasks as the ability of a
transformer to extrapolate to arbitrary task sizes with controllable error and logarithmic sample adaptation, providing a sharp scaling criterion for distinguishing logic internalization from statistical interpolation. Empirically, across scaling ranges spanning up to 2.5 orders of magnitude, we observe evidence of capture and non-capture. By analyzing infinite-width
transformers in both the lazy and rich regimes, we derive upper bounds on the inference-time computational complexity of the combinatorial tasks these networks can capture. We show that, despite their universal expressivity,
transformers possess an inductive bias that disfavors higher-complexity algorithmic procedures within the efficient
polynomial-time heuristic scheme class, consistent with successful capture on simpler combinatorial tasks such as induction heads, sort, and string matching.
Read the full abstract ▾
Strongly Correlated Electrons
Moiré in $\Gamma$-valley square lattice: Copper- and iron-based superconductor simulation in a single device
Toshikaze Kariyado, Yusuf Wicaksono, Ashvin Vishwanath et al. (+2 more)
Novel superconducting phases have been found in various moiré
heterostructures based on hexagonal
lattices. However, the archetypal high-temperature
superconductors (cuprates, iron-based and nickelate families) all share a square
lattice foundation. These materials host a rich landscape of correlated phenomena, such as charge and
spin stripes, pseudogap behavior, and unconventional
metallicity, which continue to challenge our fundamental understanding of strongly correlated electrons. In this work, we investigate the possibility of simulating the effective models governing these high-$T_c$
superconductors using twisted homobilayers of $\Gamma$-valley square-
lattice systems. We develop a universal theoretical framework and carry out a detailed analysis of a promising candidate material ZnF$_2$. We find that the first moiré band realizes a single-orbital square-
lattice Hubbard model, widely believed to capture cuprate physics, while the second and third moiré bands map to a $p_x,p_y$ two-orbital square-
lattice Hubbard model, which shares common physics to the minimal $d_{xz}, d_{yz}$ models proposed for iron pnictides. Our study combines continuum
Hamiltonian modeling, first-principle calculations, and Hartree-Fock mean field theory. The latter focuses on the quarter-filling regime of the two-orbital model and in particular leads to, among others, a stable antiferro-orbital,
ferromagnetic insulating phase. These results highlight $\Gamma$-valley square-
lattice moiré systems as a new and important generation of van der Waals
heterostructures to realize interesting strongly correlated phases of matter.
Read the full abstract ▾
All authors Toshikaze Kariyado, Yusuf Wicaksono, Ashvin Vishwanath, Pavel Volkov, Zhu-Xi Luo
Materials Science · Cross-listed from physics.class-ph
Nonlinear potential field in contact electrification
Benjamin J. Kulbago and James Chen
The cause of electron transfer in contact electrification is one of the most hotly debated physical problems today. In this study, the electron transfer is hypothesized to be partly driven by the surface dipole induced potential during contact. This phenomena is demonstrated by a combination of atomistic field theory (AFT) and molecular dynamics (MD) simulation. A representative contact system of carbon and silicon dioxide was chosen for its excellent tribo-tunneling power output performance. The results reveal the existence of a nonlinear potential field as well as the existence of a separation dependent potential barrier at the contact interface. Possible scenarios of triboelectric charge transfer are discussed in light of these results. These results are critical to the fundamental understanding of contact electrification.
Read the full abstract ▾
Materials Science · Cross-listed from cs.LG
Neural Field Thermal Tomography: A Differentiable Physics Framework for Non-Destructive Evaluation
Tao Zhong, Yixun Hu, Dongzhe Zheng et al. (+2 more)
Inverse problems for stiff
parabolic partial differential equations (PDEs), such as the inverse heat conduction problem (IHCP), are severely ill-posed: the forward map rapidly damps high-frequency interior structure before it reaches the boundary. Soft-constrained physics-informed neural networks (PINNs), which embed the PDE as a residual penalty, suffer from gradient pathology in this regime and tend to fit boundary measurements while leaving the interior field essentially untouched. We propose Neural Field Thermal
Tomography (NeFTY), a hard-constrained neural field framework for label-free three-dimensional inverse heat conduction. NeFTY represents the unknown diffusivity as a continuous coordinate-based neural network, and at every optimization step passes the candidate field through a differentiable implicit-Euler heat solver with harmonic-mean interface flux, so that the governing PDE holds exactly on the discretization rather than as a soft penalty. Adjoint gradients propagate the surface reconstruction error back to the network weights at solver-level
memory cost, making test-time inversion tractable on a single GPU. Across synthetic 3D
benchmarks, NeFTY substantially outperforms soft-constrained PINN variants and a voxel-grid baseline on label-free volumetric recovery, and it transfers to real thermography data, surpassing classical signal-processing baselines in both defect
segmentation and depth estimation. Additional details at https://cab-lab-princeton.github.io/nefty/
Read the full abstract ▾
All authors Tao Zhong, Yixun Hu, Dongzhe Zheng, Aditya Sood, Christine Allen-Blanchette
Quantum Gases
Realizing the Emery Model in Optical Lattices for Quantum Simulation of Cuprates and Nickelates
Hannah Lange, Liyang Qiu, Robin Groth et al. (+7 more)
The microscopic origin of high-temperature superconductivity in cuprates remains one of the central open questions in condensed matter physics. Growing experimental and theoretical evidence suggests that the bare single-band
Fermi-Hubbard model may not fully capture properties of cuprates such as superconductivity, motivating us to revisit the canonical three-band model of the copper-
oxide planes - the Emery model - from which the single-band counterpart was originally derived. Here, we propose and analyze a
quantum simulation scheme for realizing the Emery model in regimes relevant to cuprates and infinite-layer nickelates with today's ultracold atom
quantum simulation platforms, enabling the exploration of the three-band physics on system sizes that are challenging for current numerical methods. Specifically, we show that a two-dimensional optical
lattice with a superimposed pattern of repulsive potentials can be designed to study low-temperature properties for variable parameter regimes of the Emery model relevant to cuprates as well as infinite-layer nickelates. Our results pave the way for real material simulations with ultracold atom
quantum simulators and a better understanding of the physics of unconventional
superconductors.
Read the full abstract ▾
All authors Hannah Lange, Liyang Qiu, Robin Groth, Andreas von Haaren, Luca Muscarella, Titus Franz, Immanuel Bloch, Fabian Grusdt, Philipp M. Preiss, Annabelle Bohrdt
Disordered Systems and Neural Networks · Cross-listed from q-bio.NC
Inferring effective interactions and task-related brain states from large-scale neural activity with Restricted Boltzmann Machines
Nicolas Béreux, Giovanni Catania, Aurélien Decelle et al. (+3 more)
Large-scale electrophysiological recordings now enable the simultaneous monitoring of thousands of
neurons across multiple
brain regions, revealing structured variability in population activity. Understanding how such collective patterns emerge from microscopic interactions requires models that are both scalable and interpretable. Here, we use Restricted Boltzmann Machines (RBMs) to model the activity of $\sim1500$–$2000$ simultaneously recorded
neurons from the Allen Institute for
Brain Science Visual Behavior Neuropixels
dataset. Compared with conventional pairwise maximum-likelihood approaches, RBMs require substantially fewer parameters, can be trained within minutes, and accurately reproduce higher-order and global empirical statistics. They remain interpretable by defining effective interactions between
neurons, including higher-order terms, and uncover dominant coordination patterns that reflect anatomical organization. Analysis of the learned free-energy landscape further identifies task-related
brain states, while Monte Carlo sampling captures the global relaxation dynamics observed in the data. These results establish RBMs as efficient, scalable, and interpretable tools for extracting statistical structure from large-scale neural recordings and linking collective neural activity to
brain organization and behavior.
Read the full abstract ▾
All authors Nicolas Béreux, Giovanni Catania, Aurélien Decelle, Francesca Mignacco, Alfonso de Jesús Navas Gómez, Beatriz Seoane
Strongly Correlated Electrons
Two-Body Solution and Instabilities along Streda Lines in Moire Flat Bands
Guopeng Xu and Chunli Huang
Moire minibands in twisted homobilayer
semiconductors can, under suitable approximations, be modeled as a pair of Landau levels with opposite Chern numbers. This provides a minimal model for searching novel topological states in a time-reversal-symmetric
Hamiltonian. In this work, we investigate the effects of an external
magnetic field in this model. We study the many-body ground state in the density-
magnetic-field (n-B) plane along the dn/dB = \pm1/Phi0 Streda line with Hartree-Fock approximation. Away from charge neutrality, we find the Chern-insulating (incompressible) state is very robust while towards charge neutrality, we find a transition from incompressible phase to compressible phase as the interaction strength kappa decreases. Using time-dependent mean-field theory, we further analyze
spin-flip excitations and find that the incompressible state along Streda line toward charge neutrality becomes unstable even at large kappa when
magnetic field is sufficiently large. Finally, we solve the two-body problem in a given Landau level exactly where the two particles experience unequal
magnetic fields using a new basis called center-of-charge basis. This basis allows any isotropic interaction to be parameterized by a single
quantum number, the relative angular momentum, thereby extending the Haldane pseudopotentials to the unequal-
magnetic-fields case. As the difference of the two
magnetic fields varies, these pseudopotentials show a sequence of level crossings, leading to non-monotonic structure of pseudopotentials that is absent in ordinary Landau level systems. Our formulation provides a useful starting point for studying weak-field physics in moire flat bands, where
magnetic Bloch-state basis becomes computationally impossible due to the large basis sizes.
Read the full abstract ▾
Strongly Correlated Electrons
Dzyaloshinskii-Moriya-driven instabilities in square-kagome quantum antiferromagnets
Leonid S. Taran, Arnaud Ralko, Fedor V. Temnikov et al. (+3 more)
Decorated square-kagome
quantum antiferromagnets provide a natural setting in which strong frustration,
lattice decoration, and
spin-orbit-induced anisotropy compete on comparable energy scales. Here we show that in Na$_6$Cu$_7$BiO$_4$(PO$_4$)$_4$Cl$_3$ the coupling ($J_{10}$) which links the decorating Cu(3) sites to the square-kagome backbone, stabilizes the gapped
quantum-paramagnetic regime, while
symmetry-allowed Dzyaloshinskii-Moriya (DM) interactions systematically suppress the minimum spinon gap $\Delta_{\mathrm{spinon}}$ and drive the system toward
magnetic condensation. To establish this, we combine ab initio calculation of the DM vectors with a generalized Schwinger-
boson self-consistent mean-field theory that treats singlet and triplet hopping/pairing channels on equal footing. As a
benchmark, the isotropic square-kagome Heisenberg model exhibits four competing low-energy saddle points distinguished by their Wilson-loop fluxes and by characteristic static and dynamical structure-factor fingerprints. A minimal DM perturbation does not qualitatively reshape this competing landscape, but already enhances the tendency towards order. For the realistic decorated
Hamiltonian, finite-size scaling of $\Delta_{\mathrm{spinon}}$ together with momentum-resolved structure factors identifies $J_{10}$ (exchange with decorating Cu) as the control parameter of the gapped regime and shows that the full
symmetry-allowed DM pattern shifts the system further toward condensation. Our results place Na$_6$Cu$_7$BiO$_4$(PO$_4$)$_4$Cl$_3$ in close proximity to a
magnetic instability and provide experimentally testable predictions for anisotropy-enhanced soft modes in decorated square-kagome materials.
Read the full abstract ▾
All authors Leonid S. Taran, Arnaud Ralko, Fedor V. Temnikov, Vladimir V. Mazurenko, Sergey V. Streltsov, Yasir Iqbal
Soft Condensed Matter
Theory of Cell Body Lensing and Phototaxis Sign Reversal in "Eyeless" Mutants of $Chlamydomonas$
Sumit Kumar Birwa, Ming Yang, Adriana I. Pesci et al. (+1 more)
Phototaxis of many species of green algae relies upon directional sensitivity of their membrane-bound photoreceptors, which arises from the presence of a pigmented "eyespot" behind them that blocks light passing through the
cell body from reaching the photoreceptor. A decade ago it was discovered that the spherical
cell body of the alga $Chlamydomonas~reinhardtii$ acts as a lens to concentrate incoming light, and that in "eyeless" mutants of $Chlamydomonas$ the consequence of that focused light reaching the photoreceptor from behind is a reversal in the sign of phototaxis relative to the wild type behavior. We present a quantitative theory of this sign reversal by completing a recent simplified analysis of
lensing [Yang, et al., Phys. Rev. E 113, 022401 (2026)] and incorporating it into an adaptive model for $Chlamydomonas$ phototaxis. This model shows that phototactic dynamics in the presence of
lensing is subtle because of the existence of internal light caustics when the cellular index of refraction exceeds that of water. During each period of cellular rotation about its body-fixed axis, the photoreceptor receives two competing signals: a relatively long, slowly-varying signal from the direct illumination, and a stronger, shorter, rapidly-varying lensed signal. The reversal of the sign of phototaxis is then a consequence of the dominance of the flagellar photoresponse to the signal with the higher time derivative. These features lead to a quantitative understanding of phototaxis sign reversal, including bistability in the direction choice, a prediction that can be tested in single-
cell tracking studies of mutant phototaxis.
Read the full abstract ▾
All authors Sumit Kumar Birwa, Ming Yang, Adriana I. Pesci, Raymond E. Goldstein
Statistical Mechanics
Violating the All-or-Nothing Picture of Local Charges in Non-Hermitian Bosonic Chains
Mizuki Sanatani and Naoto Shiraishi
We present explicit counterexamples to a widespread empirical expectation that local commuting charges display all-or-nothing behavior. In the class of bosonic chains with symmetric nearest-neighbor hopping and arbitrary on-site terms (including non-Hermitian terms), we exhibit systems that possess k-local charges for some but not all k. Concretely, we construct non-Hermitian models with a 3-local charge but no other nontrivial local charges and models with k-local charges for all k except k = 4. These results show that the Grabowski–Mathieu integrability test based on 3-local charges is not universally applicable. We further give necessary and sufficient conditions for the existence of k-local charges in this class, yielding an exhaustive classification and uncovering additional integrable models.
Read the full abstract ▾
Materials Science
Island Sliding Barriers: A first-principles metric for determining remote epitaxy viability
Quinn T. Campbell, Manny Xavier de Jesus Lopez, Anthony Rice et al. (+6 more)
Remote epitaxy, where a 2D van der Waals material (usually
graphene) is inserted on top of the substrate before film epitaxy, has emerged as a promising path for growing electronics with lower defect rates and less stringent
lattice matching requirements. The exact mechanism behind remote epitaxy has not been definitively shown, however, and it is not obvious when examining a new substrate-film pair whether they would be compatible with the remote epitaxy process. In this paper, we use first principles calculations to test several different mechanisms for determining whether a given substrate-film pair will successfully be grown with remote epitaxy. We find that previously calculated metrics such as electrostatic potential do not hold sufficient explanatory power. We find that the sliding barrier of small islands on the surface when the atomic positions are allowed to optimize provides the most rigorous criteria for whether a given substrate-film pair is remote epitaxy active. This indicates that remote epitaxy is likely a phenomenon related to the kinetics and ease of island migration on the
graphene surface.
Read the full abstract ▾
All authors Quinn T. Campbell, Manny Xavier de Jesus Lopez, Anthony Rice, Timothy J. Ruggles, Taisuke Ohta, Caitlin McCowan, Sadhvikas Addamane, Scott W. Schmucker, Justine Koepke
Mesoscale and Nanoscale Physics
Microscopic screening theory for excitons in two-dimensional materials: A bridge between effective models and ab initio descriptions
P. Ninhos, A. J. Uría-Álvarez, C. Tserkezis et al. (+2 more)
We present a computational approach for
exciton calculations in two-dimensional (2D) materials within the Bethe-Salpeter equation (BSE) framework, employing an atomistic description with point-like orbitals. Unlike widespread efficient calculations that rely on classical or effective interaction models, such as the Rytova-Keldysh model, our method incorporates
quantum screened interactions. By explicitly computing the 2D dielectric function at the random-phase approximation level, we capture screening effects beyond such approximations with an accuracy akin to first-principles methods. Consequently, we can realistically estimate excitonic binding energies with a bearable computational cost. A detailed account of the various convergence parameters sheds light on a possible cause of the large dispersion of binding energies reported in the literature using first-principles GW/BSE implementations. This work thus provides an alternative pathway towards efficient and faithful dielectric screening and
exciton computations in low-dimensional materials.
Read the full abstract ▾
All authors P. Ninhos, A. J. Uría-Álvarez, C. Tserkezis, N. A. Mortensen, J. J. Palacios
Disordered Systems and Neural Networks · Cross-listed from q-bio.NC
Linear Readout of Neural Manifolds with Continuous Variables
Will Slatton, Chi-Ning Chou and SueYeon Chung
Brains and artificial neural networks compute with continuous variables such as object position or stimulus orientation. However, the complex variability in neural responses makes it difficult to link internal representational structure to task performance. We develop a statistical-mechanical theory of regression capacity that relates linear decoding efficiency of continuous variables to
geometric properties of neural
manifolds. Our theory handles complex neural variability and applies to real data, revealing increasing capacity for decoding object position and size along the monkey visual stream.
Read the full abstract ▾
Superconductivity
Ab-initio superfluid weight and superconducting penetration depth
Kaja H. Hiorth, Martin Gutierrez-Amigo, Théo Cavignac et al. (+3 more)
Machine learning and high-throughput screening approaches to
superconductor discovery require physically meaningful descriptors that capture essential physics while remaining computationally tractable. The superfluid weight is an ideal descriptor as it is a prerequisite for superconductivity, determines the
magnetic penetration depth and the Berezinskii-Kosterlitz-Thouless transition temperature in two-dimensional materials, may limit the critical temperature in unconventional
superconductors through phase coherence, and reveals
quantum geometric contributions to supercurrent transport. We develop a computationally efficient framework for calculating the zero-temperature, mean-field superfluid weight for uniform pairing from density functional theory band structures and Bloch wavefunctions. We separately evaluate the conventional contribution from band
curvature and the
geometric contribution from
quantum geometry. To validate the method, we calculate London penetration depths for a few conventional
superconductors (Al, Pb, Nb, MgB$_2$, LuRu$_3$B$_2$ and YRu$_3$B$_2$) and find good agreement with experiment after accounting for nonlocal corrections, strong-coupling effects, and sample quality. The conventional contribution dominates by orders of magnitude in these wide-band materials, as expected. This framework provides a foundation for large-scale screening of superconducting candidates and exploring
quantum geometric effects in unconventional
superconductors.
Read the full abstract ▾
All authors Kaja H. Hiorth, Martin Gutierrez-Amigo, Théo Cavignac, Kristjan Haule, Miguel A.L. Marques, Päivi Törmä
Materials Science
Importance of nonlinear long-range electron-phonon interaction for the carrier mobility of anharmonic halide perovskites
Matthew Houtput, Ingvar Zappacosta, William Wenborn et al. (+4 more)
The interaction between the electrons and the
lattice vibrations in a solid is responsible for various important effects, such as formation of polarons, temperature dependent bandgaps,
phonon-limited carrier transport, and conventional superconductivity. Most works assume a linear electron-
phonon interaction, where the electron only interacts with one
phonon at a time. However, the validity of this assumption has not been verified in polar anharmonic materials, where large ionic displacements may invalidate the assumption of linear interaction. Here, we show that nonlinear electron-
phonon interactions contribute significantly to the finite-temperature electron mobility of the inorganic lead halide perovskite CsPbI$_3$. The effect of nonlinear interaction is taken into account using the recently derived expression for the long-range part of the one-electron-two-
phonon matrix element. We calculate the electron mobility from first principles within the self-energy relaxation-time approximation, treating the electron-
phonon coupling in the long-range approximation. Despite these approximations, the calculated mobilities are in good agreement with the available experimental data, while enabling us to isolate and quantify the contribution of nonlinear electron-
phonon interactions relative to the conventional linear coupling. We find that the one-electron-two-
phonon interaction modifies the temperature dependence of the mobility in CsPbI$_3$ and reduces its room-temperature value by about 10%. This sizeable contribution results from the combined effects of strong
lattice anharmonicity and large thermal
phonon populations, the latter being enhanced by the low
phonon frequencies associated with the heavy constituent atoms. These results show when nonlinear electron-
phonon interactions become relevant, and indicate they should be considered for finite-temperature properties of halide perovskites.
Read the full abstract ▾
All authors Matthew Houtput, Ingvar Zappacosta, William Wenborn, Serghei Klimin, Samuel Poncé, Jacques Tempere, Cesare Franchini
Strongly Correlated Electrons
Generalized Reduced-Density-Matrix Quantum Monte Carlo Gives Access to More
Zhiyan Wang, Zhe Wang, Bin-Bin Mao et al. (+1 more)
For a long time, people have been focusing on how to extract more information, such as off-diagonal observables, from the
quantum Monte Carlo (QMC) simulation of the partition function, but there have been numerous difficulties, and many of them are insurmountable. In this article, we point out that all the difficulties stem from the starting point of the simulation: calculating a partition function. We introduce a paradigm shift: when we transform the simulated object from a partition function to a generalized reduced density
matrix (GRDM), the difficult problem of measurement can be readily solved. By designing the GRDM, both equal-time and nonequal-time off-diagonal observables have been measured easily in QMC with a
polynomial computation complexity. As a demonstration, the GRDM enables direct access to nonequal-time correlators for dynamical spectra as well as Rényi-1 correlators that reveal strong-to-weak
symmetry breaking in the mixed state, capabilities that lie beyond the reach of prior methods. This establishes a unified framework for
holographic characterization within QMC.
Read the full abstract ▾
All authors Zhiyan Wang, Zhe Wang, Bin-Bin Mao, Zheng Yan
Soft Condensed Matter · Cross-listed from physics.flu-dyn
Spectral methods for wedge and corner flows: The Fourier-Kontorovich-Lebedev integral transform
Abdallah Daddi-Moussa-Ider
Understanding fluid flow in wedge-shaped geometries is essential for predicting hydrodynamic interactions in confined systems, such as microfluidic devices and near-corner transport phenomena. This article reviews analytical methods and techniques for addressing wedge problems in low-Reynolds-number hydrodynamics, focusing on solutions of the Stokes equations for a point force (Stokeslet) and a point torque (rotlet). The formulation is based on the Papkovich-Neuber representation, which uses four harmonic functions to characterize the fluid flow. A concise overview of the
Fourier-Kontorovich-Lebedev (FKL) transform method is provided, highlighting key properties and steps employed in deriving these solutions. This offers a versatile framework for predicting particle dynamics in wedge confinements and for designing microfluidic systems with corner geometries.
Read the full abstract ▾
Materials Science · Cross-listed from physics.chem-ph
Nuclear Quantum Effects in Multi-Step Condensed Matter Chemistry: A Path Integral Molecular Dynamics Study of Thermal Decomposition
Jalen Macatangay and Alejandro Strachan
Nuclear quantum effects (NQEs) are often central to a predictive understanding of chemical reactions and rates. While their incorporation in gas-phase reactions is well established, studies involving condensed matter often neglect or approximate such effects. To clarify the role of NQEs in multi-step, multi-molecular reactions in a molecular
crystal, we compare atomistic simulations of the thermal decomposition of the energetic material TATB using path integral molecular dynamics (PIMD), the more approximate
quantum thermal bath (QTB), and classical MD (ClMD). PIMD samples the
quantum canonical distribution by representing each atom as a string of beads (replicas), while QTB uses a frequency-dependent thermostat to reproduce the Bose-Einstein distribution. We find that PIMD results in faster chemical decomposition of the TATB
crystal compared to ClMD, as the initial steps involve hydrogen transfer processes. Interestingly, some of the subsequent reactions (e.g. the formation of N2) occur on identical timescales. The PIMD simulations also predict a reduction in overall activation energy by ~8% as compared to the classical result. As observed in model systems and simple unimolecular gas-phase reactions, the QTB significantly overestimates
quantum acceleration of chemical reactions and the reduction in activation energy. A comparison of the kinetic energy operator in PIMD and the centroid dynamics provides insight into the physics behind the differences between the QTB and PIMD results.
Read the full abstract ▾
Materials Science · Cross-listed from cs.CE
An Atlas of Extreme Properties in Cubic Symmetric Metamaterials
Sahar Choukir, Nirosh Manohara and Chandra Veer Singh
Current research on three-dimensional metamaterial has largely focused on conventional strut, plate, and shell-based
lattice designs. Although these designs offer several advantages, they possess inherent limitations that can restrict their performance in certain applications, motivating the exploration of alternative structural
topologies. Here, we present a large-scale,
symmetry guided framework for the generation and analysis of architected metamaterials based on all 36 cubic space groups. Using a voxel-based representation, we construct a database of approximately 1.95 million periodic unit
cells spanning a broad range of relative densities and topological complexity. This
dataset reveals a rich elastic property landscape shaped by crystallographic
symmetry, including rare pentamode designs with high bulk to shear ratios such as $K/G \approx 166$ , isotropic-auxetic architectures with Poisson's ratio as low as $\nu=-0.76$, and structures achieving up to 93% of the Hashin-Shtrikman upper bound on stiffness. Complementing the
dataset, we develop a three-dimensional convolutional neural network surrogate model trained and evaluated on the full database to predict strain-energy density values under uniaxial, shear, and hydrostatic loading. Together, this work establishes a comprehensive atlas of cubic symmetric metamaterials and provides a pre-trained model for the accelerated discovery and design of 3D architected materials with extreme mechanical properties.
Read the full abstract ▾