Peer Revenue Publish or profit

Papers

Fresh from arXiv, typeset properly. Highlighted words trade on the market.

Physics Condensed Matter

cond-mat Watch Condensed Matter

Sunday 15 March

Materials Science

Emergent giant topological Hall effect in twisted Fe3GeTe2 metallic system

Hyuncheol Kim, Kai-Xuan Zhang, Yu-Hang Li et al. (+3 more)

The topological Hall effect, driven by the exchange interaction between conduction electrons and topological magnetic textures such as skyrmions, is a powerful probe for investigating the topological properties of magnetic materials. Typically, this phenomenon arises in systems with broken global inversion symmetry, where Dzyaloshinskii-Moriya interactions stabilize such textures. Here, we report the discovery of an emergent giant topological Hall effect in the twisted Fe3GeTe2 metallic system, which notably preserves the general global inversion symmetry. This effect manifests exclusively within a narrow window of "magic" twist angles ranging from 0.45{\deg} to 0.75{\deg}, while it is absent identically outside of that range, highlighting its unique and emergent nature. Micromagnetic simulations reveal that this topological Hall effect originates from a skyrmion lattice induced by alternating in-plane and layer-contrasting Dzyaloshinskii-Moriya interactions that result from local inversion symmetry breaking. Our findings underscore twisted Fe3GeTe2 as a versatile platform for engineering and controlling topological magnetic textures in metallic twisted van der Waals magnets, thereby opening up new avenues for next-generation spintronic devices.
Read the full abstract

All authors Hyuncheol Kim, Kai-Xuan Zhang, Yu-Hang Li, Giung Park, Ran Cheng, Je-Geun Park

Soft Condensed Matter · Cross-listed from physics.flu-dyn

Sign-Indefinite Helicity and the Structure of Weak Turbulence in Inertial and Non-Hermitian Waves

Shahaf Aharony Shapira and Michal Shavit

We investigate how sign-indefinite quadratic invariants shape turbulent cascades in incompressible flows with broken time-reversal symmetry, where the dynamics supports strongly anisotropic dispersive waves. Focusing on rotating Euler flow and odd-viscous Euler flow, we isolate the wave component study the corresponding weak-turbulence kinetic equation. We show that helicity conservation substantially simplifies the kinetic equation. Fixing the energy flux by a natural gauge choice, we identify the turbulent spectrum as the unique scale-invariant solution that sustains a constant flux of energy from large to small scales. Under a mild approximation motivated by the accumulation of energy near slow modes, we compute the leading angular dependence and uncover an integrable singularity along the slow-mode curve, that agrees with previous results. We then demonstrate that helicity reorganizes cascade directions at the level of resonant triads. Although helicity is globally sign-indefinite, the helical decomposition splits it into sign-definite contributions on each polarization branch. Triads whose three legs lie on the same branch behave as if constrained by a sign-definite invariant and drive an upscale transfer of energy, producing systematic backscatter even when the net cascade is direct. In the helicity-definite limit (single-branch dynamics), the kinetic equation admits an additional scale-invariant solution associated with helicity transport. Finally, we validate the analytical predictions by numerically evaluating the collision integral in the strongly anisotropic limit, revealing a family of stationary solutions in that regime.
Read the full abstract

Mesoscale and Nanoscale Physics · Cross-listed from physics.optics

Minkowski-Space Modeling of Hyperbolic Lenses

Enrico Maria Renzi, Simon Yves, Sveinung Erland et al. (+3 more)

The extreme anisotropy of hyperbolic materials enables extreme wave confinement, but it is also associated with an inherent misalignment between phase and energy flow, which complicates device modeling and design. Here we introduce a Minkowski-space approach to describe hyperbolic wave propagation, showing that this complexity is geometric rather than physical. By embedding anisotropy into an effective Lorentzian metric, we establish a rational design framework for hyperbolic interfaces and lenses, and analytically derive their transfer function and resolution limits, enabling ultra-large numerical apertures and deep sub-diffraction focusing. We validate our theory with the design and full-wave modeling of a planar van der Waals polaritonic lens operating in the mid-infrared frequency range.
Read the full abstract

All authors Enrico Maria Renzi, Simon Yves, Sveinung Erland, Diana Strickland, Eitan Bachmat, Andrea Alù

Statistical Mechanics

Coarsening in the long-range Persistent Voter Model

Jeferson J. Arenzon, F. Corberi, W. G. Dantas et al. (+1 more)

We investigate the coarsening kinetics in a long-range variant of the Persistent Voter Model in space dimensions $d=1$ and 2. In this model, agents can hold two confidence levels, normal and zealot. Normal agents imitate another opinion chosen at a distance $r$ with probability $P(r) \propto r^{-\alpha}$, with $\alpha >d$. On the contrary, while in the zealot state, agents keep their own opinion. Normal (zealot) agents can become zealots (normal) if their opinion is equal (different) to that of the chosen neighbour. Through numerical simulations we show that, for any values of $\alpha$, the model belongs to the same universality class of the long-range Ising model quenched to a small (non-zero) temperature, similarly to what was already known for the nearest-neighbor case. For the one-dimensional case, we further develop an analytical treatment, which reproduces the $\alpha$-dependence of the correlation length and the functional form of the correlation function. These results not only confirm that the introduction of opinion inertia mitigates the strong interfacial noise present in the Voter model, thus reinstating the basic kinetic mechanism of the Ising model, but also expand the applicability of this correspondence.
Read the full abstract

All authors Jeferson J. Arenzon, F. Corberi, W. G. Dantas, L. Smaldone

Statistical Mechanics

Breakdown of Linear Response Induced by Velocity-Dependent Stochastic Resetting

Yuto Takeishi and Takuma Akimoto

Linear response theory lies at the foundation of transport phenomena, predicting that physical systems respond proportionally to weak external forces. Here we show that this principle can break down in a minimal nonequilibrium setting due to state-dependent stochastic resetting. We consider a driven Langevin particle subject to a resetting mechanism whose rate grows as a power of the particle velocity, motivated by transport processes where faster carriers experience more frequent scattering events. We derive the exact steady-state velocity distribution and establish a moment balance relation that links external driving, viscous dissipation, and resetting-induced dissipation. This relation reveals that the response is controlled by a nonlinear coupling between the velocity and the resetting rate, leading to nonlinear transport. In particular, the mean velocity obeys the exact power law $\langle v\rangle \propto F^{1/(\alpha+1)}$, where $\alpha$ characterizes the velocity dependence of the resetting rate. Our results provide a solvable example in which linear response fails at the level of the leading-order behavior and identify velocity-dependent resetting as a minimal dynamical mechanism for generating nonlinear transport in nonequilibrium steady states.
Read the full abstract

Saturday 14 March

Materials Science

Lightweight phase-field surrogate for modelling ductile-to-brittle transition through phenomenological elastoplastic coupling

P G Kubendran Amos

The ductile-to-brittle transition (DBT) in body-centred cubic systems is a central design constraint for cryogenic structures. Performing parametric studies to enhance the understanding on DBT using fully coupled thermomechanical continuum DBT models is computationally expensive. Therefore, in this work, a lightweight phase-field surrogate is proposed. This surrogate approach captures key DBT-like trends within a standard isothermal two-field (displacement–damage) setting by prescribing temperature dependence through three phenomenological mechanisms: (i) a temperature-dependent degradation exponent $n(T)$ that sharpens stiffness loss from gradual (ductile-like, $n=2.0$ at 293\,K) to abrupt (brittle-like, $n=3.5$ at 77\,K), (ii) temperature-dependent yield stress and elastic modulus to modulate the balance between plastic dissipation and elastic energy storage, and (iii) an effective fracture toughness and driving-force scaling to represent reduced crack-tip shielding at cryogenic temperatures. The model is implemented in FEniCSx using small-strain $J_2$ return mapping and a staggered solution scheme. Simulations of a single-edge-notched specimen over 77–293\,K demonstrate a systematic progression from brittle-like to ductile-like response, characterised by reduced displacement to unstable fracture, a transition from abrupt post-peak load drop to extended softening, and a shift from narrow, localised damage bands with confined plasticity to broader process zones. A sensitivity study comparing four interpolation schemes (linear, smoothstep, exponential, hybrid) shows that the qualitative transition trends are robust, with interpolation primarily affecting intermediate-temperature responses while endpoint behaviours remain unchanged.
Read the full abstract

Materials Science · Cross-listed from physics.chem-ph

The Python Simulations of Chemistry Framework: 10 years of an open-source quantum chemistry project

Qiming Sun, Matthew R Hermes, Xiaojie Wu et al. (+100 more)

Over the past decade, the Python-based Simulations of Chemistry Framework (PySCF) has developed into a widely used open-source platform for electronic structure theory and quantum chemical method development. This article reviews the major advances since the previous overview in 2020, covering new modules and methodology, infrastructure changes, and performance benchmarks.
Read the full abstract

All authors Qiming Sun, Matthew R Hermes, Xiaojie Wu, Huanchen Zhai, Xing Zhang, Abdelrahman M. Ahmed, Juan José Aucar, Oliver J. Backhouse, Samragni Banerjee, Peng Bao, Nikolay A. Bogdanov, Kyle Bystrom, Frédéric Chapoton, Ning-Yuan Chen, Ivan Yu. Chernyshov, Helen S. Clifford, Sander Cohen-Janes, Zhi-Hao Cui, Yann D. Damour, Nike Dattani, Linus Bjarne Dittmer, Sebastian Ehlert, Janus Juul Eriksen, Francesco A. Evangelista, Simon A. Ewing, Ardavan Farahvash, Kevin Focke, Yang Gao, Kevin E. Gasperich, Nathan Gillispie, Jonas Greiner, Matthew R. Hennefarth, Jan Hermann, Christopher Hillenbrand, Joonatan Huhtasalo, Basil Ibrahim, Bhavnesh Jangid, Alireza Nejati Javaremi, Andrew J. Jenkins, Yu Jin, Daniel S. King, Derk Pieter Kooi, Jo S. Kurian, Henrik R. Larsson, Bryan Tak Gwong Lau, Seunghoon Lee, Susi Lehtola, Chenghan Li, Hao Li, Jiachen Li, Rui Li, Shuhang Li, Aleksandr O. Lykhin, Ankit Mahajan, Nastasia Mauger, Pablo del Mazo-Sevillano, Jonathan Moussa, Kousuke Nakano, Verena A. Neufeld, Linqing Peng, Hung Q. Pham, Peter Pinski, Pavel Pokhilko, Zhichen Pu, Yubing Qian, Stephen Jon Quiton, Wanja T. Schulze, Thais R. Scott, Aniruddha Seal, James D. Serna, James E. T. Smith, Kori E. Smyser, Terrence Stahl, Chong Sun, Kevin J. Sung, Egor Trushin, Shiv Upadhyay, Ethan A. Vo, Thijs Vogels, Shirong Wang, Tai Wang, Xiao Wang, Xubo Wang, Yuanheng Wang, Mark Williamson, Junjie Yang, Hong-Zhou Ye, Chia-Nan Yeh, Haiyang Yu, Jincheng Yu, Victor Wen-zhe Yu, Chaoqun Zhang, Dayou Zhang, Yichi Zhang, Zijun Zhao, Zehao Zhou, Andrew J. Zhu, Tianyu Zhu, Timothy C. Berkelbach, Laura Gagliardi, Sandeep Sharma, Alexander Sokolov, Garnet Kin-Lic Chan

Statistical Mechanics

Parity superselection obstructs monogamy of mutual information in free fermions

Aleksandrs Sokolovs

We prove that free fermions in the spin (tensor product) factorization violate monogamy of mutual information: $I_3^{\mathrm{spin}} > 0$ for adjacent strips of width $w \le 6$ at all Fermi momenta, and for all $w$ at $z = k_F w < z^* \approx 1.329$. Many-body computation at $w=6$ via the $G$-matrix formula maps the scaling-limit function $I_3^{\mathrm{spin}}(z)$: it has a minimum of $0.100$ at $z \approx 1.5$, numerically establishing the conjecture $I_3^{\mathrm{spin}} > 0$ for all $z$ and $w$. The proof rests on an exact identity: the fermionic and spin reduced density matrices of disjoint regions $A$, $D$ separated by $B$ differ by the parity insertion $(-1)^{N_B}$ in the partial trace. A Perron–Frobenius argument proves element-wise coherence damping; for free fermions, an independent Gaussian bound gives the entropy ordering $\Delta S_{AD} \ge 0$. Exact diagonalization confirms this for interacting fermions. DMRG on the $t$-$V$ chain shows that the factorization contribution exceeds the genuine interaction contribution to $I_3$ by a factor of 8, accounting for $\sim 80\%$ of the deviation in spin-basis numerics. Strong repulsion ($K \lesssim 0.7$) restores monogamy. Conversely, $Z_2$ parity superselection enforces $I_3 \le 0$ at all fillings (proved for $w \le 3$), with the ratio of parity entropy to quantum excess approaching $2\ln 2/(3\ln(4/3)) = 1.606$. Any use of $I_3$ as a diagnostic for holographic duality, quantum chaos, or Fermi surface topology must specify the operator algebra; without this, the sign of $I_3$ is ambiguous.
Read the full abstract

Materials Science

Digital Hydrogen Platform (DigHyd): A Rigorously Curated Database for Hydrogen Storage Materials Empowered by AI-Assisted Literature Mining

Seong-Hoon Jang, Di Zhang, Xue Jia et al. (+8 more)

Solid-state hydrogen storage materials are promising candidates for safe and compact hydrogen storage; however, data-driven discovery in this field remains limited by the availability of large-scale, well-curated datasets. Here, we present the Digital Hydrogen Platform (DigHyd: www.dighyd.org), a rigorously curated database comprising $>4,000$ experimental literature sources and $>30,000$ data entries on hydrogen storage materials, constructed through AI-assisted literature mining combined with human-in-the-loop validation. In addition to gravimetric hydrogen storage density ($w$), DigHyd also covers thermodynamic parameters, specifically the enthalpy ($\Delta H$) and entropy ($\Delta S$) changes associated with hydrogenation reactions, primarily defined as $M + \frac{1}{2} {\rm H}_2 \rightleftarrows M{\rm H}$. These parameters were obtained by manually analyzing multi-temperature pressure-composition-temperature (PCT) data using van't Hoff analysis. By focusing on $\Delta H$ and $\Delta S$ rather than fixing equilibrium pressure at a single temperature, DigHyd enables flexible evaluation of equilibrium behavior under application-specific operating conditions. Statistical analyses reveal distinct distributions of thermodynamic parameters across material classes, together with broad compositional variability within representative hydride systems. Furthermore, both physically interpretable symbolic regression and black-box XGBoost models achieve comparable predictive performance for $w$ and equilibrium pressure at room temperature ($P_{\rm eq,RT}$), demonstrating internal consistency and learnable composition-property relationships within the curated dataset. Overall, DigHyd provides a rigorously curated thermodynamic dataset that serves as a reliable basis for data-driven analyses of hydrogen storage materials and supports systematic exploration of structure-property relationships.
Read the full abstract

All authors Seong-Hoon Jang, Di Zhang, Xue Jia, Hung Ba Tran, Linda Zhang, Ryuhei Sato, Yusuke Hashimoto, Toyoto Sato, Kiyoe Konno, Shin-ichi Orimo, Hao Li

Materials Science

Effects of uniaxial strain on monolayer transition-metal dichalcogenides revisited

Igor Evangelista, Abdul Saboor, Muhammad Zubair et al. (+6 more)

Using hybrid density functional calculations including spin-orbit coupling, we compute the strain evolution of the band structure of monolayer 1H-phase transition-metal dichalcogenides, MX$_2$ (M= Mo, W; X= S, Se, Te), emphasizing an accurate reproduction of the quasiparticle band gap (as opposed to the excitonic optical gap). We show that tensile uniaxial strain applied along either the armchair or zigzag directions leads to a pronounced reduction of the fundamental gap, with the conduction-band edge generally exhibiting the stronger strain response. Both the conduction-band electron valleys (CBM) and the valence-band hole valleys (VBM) remain degenerate under uniaxial strain, while simultaneously drifting away from the high-symmetry $K$ point under strain ("valley drift"), such that the band extrema occur at nearby off-symmetry wave vectors. A minimal tight-binding model rationalizes the valley drift and the unequal electron- and hole-valley drift rates in the presence of strain, leading to indirect band gaps. In particular, for MoS$_2$ the indirectness increases with tensile strain, providing a natural explanation for the experimentally observed decrease in photoluminescence intensity under uniaxial deformation. These results provide quantitative guidance for tailoring band structures for optoelectronic and quantum-defect applications.
Read the full abstract

All authors Igor Evangelista, Abdul Saboor, Muhammad Zubair, Intuon Chatratin, Ruiqi Hu, Dai Q. Ho, Shoaib Khalid, Ioanna Fampiou, Anderson Janotti

Superconductivity

The stripe state at 1/8 Ba doping hosts optimal superconductivity in La-214 cuprates under low in-plane stress

V. Sazgari, S.S. Islam, M. Lamotte et al. (+20 more)

The cuprate system La$_{2-x}$Ba$_{x}$CuO$_{4}$ (LBCO) exhibits a pronounced sensitivity to in-plane uniaxial stress, particularly near the 1/8 doping anomaly, where stripe order strongly suppresses bulk superconductivity. While previous studies have focused on compositions close to 0.125, the commensurate $x$=0.125 phase remains largely unexplored under symmetry-selective lattice tuning. Here, we combine muon-spin rotation (${\mu}$SR), AC susceptibility, and electrical resistivity to investigate superconductivity, spin-stripe order, and structural response in LBCO-0.125 under in-plane uniaxial stress applied 45$^\circ$ to the Cu-O bond direction. Complementary resistivity measurements on $x$=0.115 and 0.135 track the evolution across both sides of the anomaly. We observe a giant enhancement of the bulk superconducting transition temperature in LBCO-0.125, increasing from 5 K to 37 K under 0.5 GPa. While the onset temperature of spin-stripe order decreases only modestly, the magnetic volume fraction is reduced by about a factor of two, with local order preserved. Simultaneously, the resistivity peak associated with the LTT phase is fully suppressed across all dopings. These results demonstrate that suppression of the LTT phase and reduction of the static spin-stripe-ordered volume fraction are crucial for the development of optimal three-dimensional superconductivity. Strikingly, the composition $x$=0.125, with the most robust stripe stability and the lowest ambient-pressure $T_{\rm c}$ develops the highest $T_{\rm c}$ under stress, reaching a zero-resistance state at 37 K and an onset of the superconducting transition as high as 46 K. This behavior indicates that stripe-related interactions enhance pairing strength, while static stripe order competes with superconductivity primarily at the level of phase coherence rather than pairing itself.
Read the full abstract

All authors V. Sazgari, S.S. Islam, M. Lamotte, J.N. Graham, O. Gerguri, P. Kràl, I. Maetsu, T. Shiroka, G. Simutis, R. Khasanov, R. Sarkar, A. Steppke, N.A. Shepelin, M. Müller, M. Bartkowiak, M. Janoschek, J. Chang, H.H. Klauss, T. Adachi, G.D. Gu, J.M. Tranquada, H. Luetkens, Z. Guguchia

Materials Science

Vacuum Wannier Functions for First-Principles Scattering and Photoemission

Tyler Wu and Tomás Arias

We establish a first-principles theory of vacuum Wannier functions unifying tight-binding and nearly-free-electron descriptions across solid-vacuum interfaces. Analytic solutions for canonical Wannier functions in arbitrary dimension and disentangled functions in 1D motivate a numerically verified 3D Wannier close-packing principle, enabling dense k-space construction of full Born-series scattering states at interfaces and thus predictive photoemission calculations without semiempirical vacuum potentials. Applications to graphene and h-BN reveal corrections beyond the first-Born approximation.
Read the full abstract

Statistical Mechanics

Intrinsic Error Thresholds in Nearly Critical Toric Codes

Zack Weinstein and Samuel J. Garratt

We study the protection of information in nearly critical topological quantum codes, constructed by perturbing topological stabilizer codes towards continuous quantum phase transitions. Our focus is on the transverse-field toric code subjected to local Pauli decoherence. Despite the strong quantum fluctuations of anyons when the transverse field is tuned infinitesimally close to the critical point, we show that a finite strength of Pauli decoherence remains necessary to irreversibly destroy information encoded in the ground-state manifold. Using a replica statistical physics mapping for the coherent information, we show that decoherence can be understood as introducing a two-dimensional inter-replica defect within a three-dimensional replica statistical physics model. A field theoretical analysis shows that this defect is perturbatively irrelevant to the bulk critical point, and cannot renormalize the transverse field strength, leading to a finite error threshold. We argue that a qualitatively similar conclusion can be drawn for a broad class of nearly critical topological codes, under a variety of decoherence channels.
Read the full abstract

Mesoscale and Nanoscale Physics

Imaging Harmonic Generation of Magnons

Anthony J. D'Addario, Kwangyul Hu, Maciej W. Olszewski et al. (+4 more)

This work combines theory and experiment to examine the mechanisms underlying the harmonic generation of magnons. We develop a nonlinear spin-wave framework that is directly analogous to harmonic generation in nonlinear optics, and combine it with scanning nitrogen-vacancy (NV) center magnetometry to image and quantify magnonic harmonic generation in a Ni$_{81}$Fe$_{19}$/Pt microstripe. Within this framework, the harmonic response arises from nonlinear magnetization dynamics localized at strongly inhomogeneous textures, such as the sample edges and domain walls, that act as anharmonic confining potentials. Scanning probe imaging confirms that the harmonic response is correspondingly nonuniform and concentrated near the sample edges. We measure an expected nonlinear power-law scaling, a systematic shift toward larger wavevector excitations at higher harmonic order, and a spin-selective response indicative of an increasingly chiral harmonic stray field. These results provide a microscopic understanding of magnonic harmonic generation and highlight its potential for engineering nonlinear functionality in magnonic systems.
Read the full abstract

All authors Anthony J. D'Addario, Kwangyul Hu, Maciej W. Olszewski, Daniel C. Ralph, Michael E. Flatté, Katja C. Nowack, Gregory D. Fuchs

Materials Science

Linear dichroic soft X-ray microscopy of ferroelectric stripe domains in epitaxial K$_\mathbf{0.6}$Na$_\mathbf{0.4}$NbO$_\mathbf{3}$

M. Schneider, T. A. Butcher, S. Wagner et al. (+19 more)

Functional properties of ferroelectric thin films are governed by domains that can be engineered by epitaxial strain. Soft x-ray microscopy can image domain structures with elemental and electronic sensitivity, but hitherto its application to strain-stabilized domains has been hindered by the absorption of soft x-rays in epitaxial substrates. Here, it is demonstrated how this limitation can be overcome by locally back-thinning the (110) TbScO3 substrate of epitaxial K$_{0.6}$Na$_{0.4}$NbO$_{3}$ ferroelectric thin films to achieve soft x-ray transparency at the O K-edge around 530 eV. Strain-induced ferroelectric stripe domains with periods down to 44 nmwere resolved by scanning transmission x-ray microscopy and coherent diffractive imaging by exploiting the x-ray linear dichroism of hybridized O 2p-Nb 4d states, providing sensitivity to in-plane polarization components under normal incidence. The results establish soft x-ray microscopy for nanoscale imaging of epitaxial ferroelectric domain structures and open perspectives for time-resolved studies thereof.
Read the full abstract

All authors M. Schneider, T. A. Butcher, S. Wagner, D. Metternich, C. Klose, E. Malm, R. Battistelli, V. Deinhart, J. Fuchs, S. Wittrock, T. Karaman, K. Puzhekadavil Joy, M. Patra, F. Büttner, S. Wintz, M. Weigand, C. M. Günther, D. Engel, P. Gaal, J. Schwarzkopf, B. Pfau, S. Eisebitt

Statistical Mechanics · Cross-listed from q-fin.CP

Conditioning on a Volatility Proxy Compresses the Apparent Timescale of Collective Market Correlation

Yuda Bi and Vince D Calhoun

We address the attribution problem for apparent slow collective dynamics: is the observed persistence intrinsic, or inherited from a persistent driver? For the leading eigenvalue fraction $\psi_1=\lambda_{\max}/N$ of S&P 500 60-day rolling correlation matrices ($237$ stocks, 2004–2023), a VIX-coupled Ornstein–Uhlenbeck model reduces the effective relaxation time from $298$ to $61$ trading days and improves the fit over bare mean reversion by $\Delta$BIC$=109$. On the decomposition sample, an informational residual of $\log(\mathrm{VIX})$ alone retains most of that gain ($\Delta$BIC$=78.6$), whereas a mechanical VIX proxy alone does not improve the fit. Autocorrelation-matched placebo fields fail ($\Delta$BIC$_{\max}=2.7$), disjoint weekly reconstructions still favor the field-coupled model ($\Delta$BIC$=140$–$151$), and six anchored chronological holdouts preserve the out-of-sample advantage. Quiet-regime and field-stripped residual autocorrelation controls show the same collapse of persistence. Stronger hidden-variable extensions remain only partially supported. Within the tested stochastic class, conditioning on the observed VIX proxy absorbs most of the apparent slow dynamics.
Read the full abstract

Mesoscale and Nanoscale Physics

Finite-Time Braiding Dynamics within Topological Nanowire Qubits

Adrian D. Scheppe and Michael V. Pak

Topological Quantum Computing has largely evolved towards a paradigm of manipulating edge localized Majorana within $p$-wave topological superconducting nanowires. To bridge the gap between physical qubit systems and quantum algorithms, we perform a dynamical analysis to extend what is known in the adiabatic regime, providing time-dependent gate elements for further qubit and algorithm modeling efforts. Our analysis covers dynamical considerations for two methods of shuttling domain edge bound Majoranas in a single nanowire system which both function by applying spatiotemporally dependent onsite and hopping parameters within the system's Hamiltonian. We then complicate this model by converting it into the T-qubit to calculate the finite-time gate representation of the shuttling techniques used in a more practical setting. These contributions provide insight for realistic experimental setups in the next-generation of qubit implementation and will hopefully facilitate fault tolerant scalable systems and universal gate design.
Read the full abstract

Statistical Mechanics

Possibilities of applying boundary functionals of random processes to nuclear safety problems

V. V. Ryazanov

The potential for using boundary functionals of random risk processes to solve nuclear safety problems at nuclear power plants is assessed. In certain situations (MSRs (Molten Salt Reactors), High-Temperature Gas-Cooled Reactors (HTGRs), pulverized fuel reactors, reactor startups, and accident analysis (core collapse)), neutron behavior changes significantly. Neutron clustering begins to play an important role, and the distributions characterizing neutron behavior change. The normal distribution is replaced by stable, but also limiting, distributions. Boundary functionals allow for precise calculation of the power quantile and provide a mathematical bridge between abstract directed percolation and engineering calculations of protection settings.
Read the full abstract

Superconductivity

Superhydrides on the way to ambient pressure: weak localization and persistent X-ray photoconductivity in BaSiH$_{8}$

Dmitrii V. Semenok, Di Zhou, Sven Luther et al. (+15 more)

Reducing the stabilization pressure of superhydrides represents one of the most important challenges in hydrogen-saturated compound chemistry. Moving in this direction, we studied the Ba-Si-H system at 0-142 GPa using transport measurements, 1H nuclear magnetic resonance, single-crystal and powder X-ray diffraction in the temperature range of 4-317 K. We synthesized the previously predicted cubic BaSiH$_{8}$ at pressures of 18-31 GPa. Remarkably, we demonstrate that BaSiH$_8$ remains stable upon decompression to ambient conditions and can be recovered from the diamond anvil cell. Obtained Ba-Si polyhydrides exhibit metallic and superconducting properties ($\textit{T$_c$}$ = 9 K, $\textit{B$_{c2}$}$(0)=13-16 T) at 142 GPa. However, at pressures below 50 GPa, these hydrides behave as degenerate semiconductors (bandgap < 0.4 meV) or poor metals with weak electron localization, negative magnetoresistance, photovoltaic effect, and persistent photoconductivity in the X-ray and visible range. Our work demonstrates the high-pressure synthesis of Ba-Si polyhydrides that remain stable upon decompression to ambient conditions, overcoming a critical bottleneck in superhydride chemistry and establishing a foundation for practical applications in hydrogen storage.
Read the full abstract

All authors Dmitrii V. Semenok, Di Zhou, Sven Luther, Toni Helm, Hirokazu Kadobayashi, Yuki Nakamoto, Katsuya Shimizu, Kirill S. Pervakov, Andrei V. Sadakov, Oleg A. Sobolevskiy, Vladimir M. Pudalov, Simone Di Cataldo, Roman Lucrezi, Lilia Boeri, Michele Galasso, Frederico G. Alabarse, Ivan A. Troyan, Viktor V. Struzhkin

Statistical Mechanics · Cross-listed from math-ph

Entropy Maximization and Weak Gibbsianity of Quasi-Free Fermionic States

Vojkan Jakšić, Claude-Alain Pillet and Anna Szczepanek

In their 1972 study of approach to equilibrium, Lanford and Robinson showed that gauge-invariant quasi-free states of lattice fermions maximize entropy among all translation-invariant states with a fixed two-point function, and suggested that the maximizer is unique. In subsequent work on this topic, the uniqueness question re-emerged, together with the problem of whether such quasi-free states are weak Gibbs states. We provide a positive answer to both questions within a class of states whose momentum-space two-point function $\widehat C$ satisfies $0<\widehat C(k)<1$ and belongs to the Wiener algebra of the Brillouin zone. The proof reveals that both the entropy maximization principle and weak Gibbsianity follow directly from the thermodynamic formalism for lattice fermions.
Read the full abstract

Materials Science

Non-isothermal flow of Al-, Co- and Cu-based alloys made in different spatial configurations or structural states: model and experimental study

A.D. Berezner, V.A. Fedorov, N.S. Perov et al. (+4 more)

The universal generalising approach for non-isothermal behaviour of different alloys has been provided together with the novel deformation modelling. Strong correlation between the model approach and experimental results is shown that permits estimation of main applied parameters such as the linear thermal expansion coefficient and others. Necking contours and critical thickness at corrugation for ribbon and rod specimens are also calculated. Fractal analysis of corrugation folds (their main size) has been carried out for polycrystalline and amorphous ribbon specimens. Structural peculiarities at the plastic deformation stage are investigated with microscopy.
Read the full abstract

All authors A.D. Berezner, V.A. Fedorov, N.S. Perov, J.C. Qiao, V.E. Gromov, M.Yu. Zadorozhnyy, G.V. Grigoriev

Materials Science · Cross-listed from physics.chem-ph

Systematically Improvable Numerical Atomic Orbital Basis Using Contracted Truncated Spherical Waves

Yike Huang, Zuxin Jin, Linfeng Zhang et al. (+1 more)

To solve the Kohn-Sham equation within the framework of density functional theory, we develop a scheme to construct numerical atomic orbital (NAO) basis sets by contracting truncated spherical waves (TSWs). The contraction minimizes the trace of the kinetic operator in the residual space, generalizing the spillage minimizing scheme [M. Chen et al., J. Phys. Condens. Matter 22, 445501 (2010); P. Lin et al., Phys. Rev. B 103, 235131 (2021)]. In addition to the systematic improvability inherited from previous schemes, the use of TSW instead of plane waves as the expansion basis bridges reference states and NAOs more effectively, and eliminates spurious interactions between periodic images, thereby enabling better transferability through the inclusion of extensive reference states. Benchmarks demonstrate that the constructed NAO achieves satisfactory precision for various properties of both molecules and bulk systems, including total energy, bond length, atomization energy, lattice constant, cohesive energy, band gap, and energy-level alignment. By incorporating unoccupied states, the improved transferability in describing the conduction band is demonstrated to be effective and substantial.
Read the full abstract

All authors Yike Huang, Zuxin Jin, Linfeng Zhang, Mohan Chen

Soft Condensed Matter

Landau-de Gennes numerical simulation of nematic liquid crystals utilizing radial basis functions

Jin-Sheng Wu and Ivan I. Smalyukh

Numerical simulations based on radial basis functions have been developed for systems with complex geometries and have been successfully applied across various fields, including seismology, coastal hydrodynamics, and biology. However, examples in liquid crystal modeling are limited. In this study, we present a Landau-de Gennes numerical simulation of nematic liquid crystals utilizing radial basis functions, emphasizing its advantages over traditional cubic grid calculations, such as enhanced geometric flexibility and improved computational efficiency. Through simulations of liquid crystal-colloid systems with diverse geometries, we demonstrate that our approach effectively captures the essential topological and energetic features of liquid crystal equilibrium structures. Additionally, we introduce an adaptive node refinement scheme that is crucial for resolving the fine structure of singular defects in nematic liquid crystals.
Read the full abstract

Quantum Gases

Tomonaga-Luttinger liquid theory for one-dimensional attractive Fermi gases

Hai-Ying Cui, Yu-Hao Yeh, Randall G. Hulet et al. (+3 more)

The one-dimensional (1D) Yang-Gaudin model–an integrable $\delta$-function interacting Fermi gas, serves as a paradigm in quantum many-body physics, encompassing phenomena from spin-charge separation to the Luther-Emery liquid. However, a consistent description of the Luther-Emery liquid and the Fulde-Ferrell-Larkin-Ovchinnikov (FFLO)-like pairing states in the 1D attractive Fermi gas remains elusive. In this work, we develop a universal Tomonaga-Luttinger liquid (TLL) theory to describe the FFLO state both for the case of weak and strong binding between fermions of opposite spins. We rigorously derive a low-energy effective Hamiltonian using bosonization, revealing the emergence of a two-component TLL: one exhibiting spin-charge coupling in the weak binding regime, and another featuring charge-charge separation in the strong binding regime. For the weak binding regime, we further derive renormalization-group equations for the sine-Gordon term in the spin sector and show that this term undergoes a relevant-irrelevant phase transition driven by the magnetic field. We further analyze the dynamical correlation functions of the FFLO pairing state based on the effective Hamiltonian we constructed. Finally, we discuss experiments using ultracold atoms to elucidate the Luther-Emery liquid behavior and the subtle phenomena of spin-charge coupling and charge-charge separation.
Read the full abstract

All authors Hai-Ying Cui, Yu-Hao Yeh, Randall G. Hulet, Han Pu, Thierry Giamarchi, Xi-Wen Guan

Materials Science

Generative Inverse Design of Cold Metals for Low-Power Electronics

Kedeng Wu, Yucheng Zhu, Yan Chen et al. (+6 more)

Cold metals are a class of metals with an intrinsic energy gap located close to the Fermi level, which enables cold-carrier injection for steep-slope transistors and is therefore promising for low-power electronic applications. High-throughput screening has revealed 252 three-dimensional (3D) cold metals in the Materials Project database, but database searches are inherently limited to known compounds. Here we present an inverse-design workflow that generates 3D cold metals using MatterGPT, a conditional autoregressive Transformer trained on SLICES, an invertible and symmetry-invariant crystal string representation. We curate a training set of 26,309 metallic structures labeled with energy above hull and a unified band-edge distance descriptor that merges p-type and n-type cold-metal characteristics to address severe label imbalance. Property-conditioned generation targeting thermodynamic stability and 50-500 meV band-edge distances produces 148,506 unique candidates; 92.1% are successfully reconstructed to 3D structures and down-selected by symmetry, uniqueness and novelty filters, followed by high-throughput DFT validation. We identify 257 cold metals verified as novel with respect to the Materials Project database, with gaps around the Fermi level spanning 50-500 meV. First-principles phonon, electronic-structure, and work-function calculations for representative candidates confirm dynamical stability and contact-relevant work functions. Our results demonstrate that SLICES-enabled generative transformers can expand the chemical space of cold metals beyond high-throughput screening, providing a route to low-power electronic materials discovery.
Read the full abstract

All authors Kedeng Wu, Yucheng Zhu, Yan Chen, Bizhu Zhang, Shuyu Liu, Xiaobin Deng, Yabei Wu, Liangliang Zhu, Hang Xiao

Statistical Mechanics

Channel transport: gating, geometry, and heterogeneous diffusion

Sean D Lawley

Channel-mediated transport is ubiquitous in biology. A series of works by different theoreticians have sought to determine how the diffusive flux through a channel depends on (a) stochastic gating, (b) channel geometry, and (c) heterogeneous diffusion. In this paper, we derive an explicit estimate for the diffusive flux through a channel that accounts for these three factors. We show that our estimate is exact in certain parameter regimes. We further use stochastic simulations to confirm that our estimate remains accurate across a very broad range of parameters. Our estimate differs from some results in the physics literature.
Read the full abstract

Mesoscale and Nanoscale Physics

Extracting the Anyonic Exchange Phase from Hanbury Brown-Twiss Correlations

Felix Puster, Matthias Thamm and Bernd Rosenow

In recent years, interferometry experiments in fractional quantum Hall devices have reported signatures of a fractional braiding phase for quasiparticles. It was noted, however, that the braiding phase alone does not uniquely determine the exchange phase because of a $\pi$-ambiguity. Here we analyze a Hanbury Brown-Twiss interferometer in a cross geometry that provides direct access to the fractional exchange phase. Using a non-equilibrium Keldysh calculation in an experimentally relevant regime, we show that the exchange phase can be obtained as the phase shift between Aharonov-Bohm oscillations in a single-particle interference current and those in the current cross-correlation arising from two-particle interference.
Read the full abstract

Statistical Mechanics

Information-Driven Phase Transition on Weighted Graphs with Spontaneous Dimensional Sensitivity

Valerio Dolci

We study information flow on a weighted graph whose topology evolves according to a spectral curvature measure $\mathcal{R}$. The model (FIU) defines $\mathcal{R}$ from the diagonal of the graph Green function, propagates energy with curvature-dependent dissipation, and creates long-range links between high-$\mathcal{R}$ nodes at a rate controlled by a coupling parameter $g$. We report three results. First, the system exhibits a sharp phase transition at $g_c \approx 0.023$: below $g_c$, local information flux $\sigma$ and structure formation are anti-correlated; above $g_c$, they become strongly correlated (Pearson $r \approx 0.75$, $p < 10^{-38}$), with signatures of a continuous transition and mean-field exponent $\nu \approx 0.54$. Second, we identify a node-level discrete Poisson relation $\nabla^2\mathcal{R}(i) = \kappa\,\sigma_{\rm prev}(i)$, where $\kappa$ is stable across parameters (CV $= 3.1\%$ across independent configurations). Mediator analysis reveals this correlation is almost entirely mediated by $\mathcal{R}$ itself, identifying it as the central self-organizing variable. Third, the Poisson relation exhibits spontaneous dimensional sensitivity: in 2D lattices both signals decay for $N \gtrsim 576$, while in 3D they persist to $N \lesssim 1728$. This emerges without any dimensional parameter in the rules. The collapse mechanism is curvature homogenization at large $N$. We interpret this as topological frustration in a mesoscopic regime, and discuss analogies with dimensional signatures of gravity.
Read the full abstract

Strongly Correlated Electrons

Crystal structure, magnetic and resonant properties of decorated spin kagome system (CsCl)Cu$_5$As$_2$O$_{10}$

Ilya V. Kornyakov, Marina V. Likholetova, Irina E. Lezova et al. (+8 more)

We report the synthesis and investigation of the crystal structure and physical properties of the averievite-like arsenate, $(\mathrm{CsCl})\mathrm{Cu}_5\mathrm{As}_2\mathrm{O}_{10}$. Just above room temperature, this compound undergoes a structural phase transition from the high-temperature trigonal $P\bar{3}m1$ $(a=b=a_0$ and $c=c_0)$ to the low-temperature monoclinic $I2/a$ phase $(a \approx \sqrt{3}a_0$, $b=a_0$, $c \approx 2c_0$ and $\beta \approx 90.6^\circ)$. According to thermodynamic and nuclear magnetic resonance measurements, it experiences a phase transition into a canted antiferromagnetic state at $T_N = 21~\mathrm{K}$. The density functional theory calculations place the energy scale of kagome exchange interaction parameter in $(\mathrm{CsCl})\mathrm{Cu}_5\mathrm{As}_2\mathrm{O}_{10}$ in between those in V- and P-analogs.
Read the full abstract

All authors Ilya V. Kornyakov, Marina V. Likholetova, Irina E. Lezova, Sergey V. Krivovichev, Harald O. Jeschke, Yasir Iqbal, Alexey V. Tkachev, Sergey V. Zhurenko, Andrey A. Gippius, Larisa V. Shvanskaya, Alexander N. Vasiliev

Materials Science · Cross-listed from cs.CV

Efficient Semi-Automated Material Microstructure Analysis Using Deep Learning: A Case Study in Additive Manufacturing

Sanjeev S. Navaratna, Nikhil Thawari, Gunashekhar Mari et al. (+3 more)

Image segmentation is fundamental to microstructural analysis for defect identification and structure-property correlation, yet remains challenging due to pronounced heterogeneity in materials images arising from varied processing and testing conditions. Conventional image processing techniques often fail to capture such complex features rendering them ineffective for large-scale analysis. Even deep learning approaches struggle to generalize across heterogeneous datasets due to scarcity of high-quality labeled data. Consequently, segmentation workflows often rely on manual expert-driven annotations which are labor intensive and difficult to scale. Using an additive manufacturing (AM) dataset as a case study, we present a semi-automated active learning based segmentation pipeline that integrates a U-Net based convolutional neural network with an interactive user annotation and correction interface and a representative core-set image selection strategy. The active learning workflow iteratively updates the model by incorporating user corrected segmentations into the training pool while the core-set strategy identifies representative images for annotation. Three subset selection strategies, manual selection, uncertainty driven sampling and proposed maximin Latin hypercube sampling from embeddings (SMILE) method were evaluated over six refinement rounds. The SMILE strategy consistently outperformed other approaches, improving the macro F1 score from 0.74 to 0.93 while reducing manual annotation time by about 65 percent. The segmented defect regions were further analyzed using a coupled classification model to categorize defects based on microstructural characteristics and map them to corresponding AM process parameters. The proposed framework reduces labeling effort while maintaining scalability and robustness and is broadly applicable to image based analysis across diverse materials systems.
Read the full abstract

All authors Sanjeev S. Navaratna, Nikhil Thawari, Gunashekhar Mari, Amritha V P, Murugaiyan Amirthalingam, Rohit Batra