Mesoscale and Nanoscale Physics
Leveraging structural disorder to enhance topological phases
Laura Gomez Paz, Peru d'Ornellas and Adolfo G Grushin
On-site disorder can be leveraged to induce a transition from a trivial to a topological
insulator. However it is unclear if structural disorder in the absence of on-site disorder can aid a similar transition and, if so, which kind of structural disorder is more favourable. We numerically show that structural disorder can enhance and sustain a topological phase up to strong disorder in two dimensions provided that one penalises atomic sites from being close to one another. However, we find this effect is absent in three dimensions, where structural disorder appears generically detrimental to the phase. In our calculations we include disorder that can scramble the global
spin-reference frame, an overlooked type of disorder expected to exist in strongly disordered solids. This disorder fatally scrambles the information necessary for the
spin-Bott and the
spin-Chern marker to correctly diagnose a topological phase. By using the spectral localizer, a local marker directly defined using the time-reversal
symmetry operator rather than a
spin-projection, we show how one can circumvent this limitation, providing a basis-indifferent theory for calculating Z2 invariants. Our work showcases that not all structural disorders are equally beneficial to
topology, and highlights guiding principles to enhance and detect topological phases in both solid-state and metamaterial realisations.
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Materials Science
Hydrothermally-Assisted Sintering of Calcium Hydroxide Sputtering Targets: A Route to Quantum-Grade CaO Thin Films
Jake A. DeChiara, Tainara Coutinho, Saeed S.I. Almishal et al. (+1 more)
In this report we demonstrate dense polycrystalline calcium hydroxide ceramics fabricated by hydrothermally-assisted sintering - often referred to as cold-sintering - to produce high-purity calcium hydroxide targets for calcium
oxide thin film deposition. Calcium hydroxide ceramics exhibit up to 98% theoretical density without thermal dehydration, when sintered at temperatures between 100 {\deg}C - 300{\deg} C with 400 MPa applied uniaxial pressure for 1 hour. The brucite phase is preserved in calcium hydroxide targets at all temperatures. Small equivalent fractions of calcium carbonate are present in both the calcium hydroxide precursor powder and final targets suggesting minimal additional production during formation and densification. Microstructure
evolution during densification is documented by scanning electron microscopy, indicating both mass transport and plastic deformation densification mechanisms. The hydrothermal-assisted sintering process is scaled up to produce 2-inch diameter calcium hydroxide targets suitable for sputter deposition. We also report epitaxial calcium
oxide film deposition from these targets on r-plane sapphire substrates. (002) oriented epitaxial films are achieved with a time-stable 1.2 nm per minute deposition rate. We note that energetic bombardment during growth can be substantial at these rates even when 1 mol% oxygen is added to the sputtering process necessitating the low deposition rate conditions.
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All authors Jake A. DeChiara, Tainara Coutinho, Saeed S.I. Almishal, Jon-Paul Maria
Mesoscale and Nanoscale Physics
Nonequilibrium transport in epitaxial CsPbBr3 single crystals
Seryio Saris, Roberto Rosati, Vladimir Bruevich et al. (+5 more)
Transport of optically excited carriers in
semiconductors is typically described within a quasi-
equilibrium picture, where energy is carried by a single thermalized quasiparticle population characterized by well-defined transport coefficients. Here, we demonstrate that in epitaxial CsPbBr3 perovskite single
crystals, this picture holds near room temperature - but breaks down dramatically at low temperature. Using transient microscopy, we show that optically measured carrier mobilities match device-scale
Hall-effect and field-effect transistor measurements across a broad temperature range, resolving reported discrepancies and validating the
equilibrium framework in the free-carrier regime. Below ~60 K, however, when excitonic effects become significant,
equilibrium models begin to fail. We observe two coupled populations: a transient (<100 ps) hot-
exciton gas with a diffusivity ~25-30 cm<sup>2</sup>/s - greatly exceeding the diffusivity expected for thermalized
excitons - and a quasi-localized state that is fed by the cooling of the hot-
exciton gas. These results reveal that in CsPbBr3, transport and thermalization are not separable processes: carriers move while still redistributing among internal degrees of freedom, breaking the timescale separation that underpins
equilibrium transport theory in conventional
semiconductors. By resolving transport at the population level, we can directly access the competing kinetics of
exciton formation, interconversion, and cooling, offering a new space for controlling energy flow in perovskite materials and their photonic applications.
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All authors Seryio Saris, Roberto Rosati, Vladimir Bruevich, Thomas J. Sheehan, Maksim Roman, Vitaly Podzorov, Ermin Malic, William A. Tisdale
Quantum Gases
Chaotic spin dynamics of elongated spinor condensates
Jose Reyes-Calderón, Albert Gallemí, Carsten Klempt et al. (+1 more)
Elongated
spin-$1$ condensates present a highly non-trivial local magnetization dynamics, due to the interplay between nonlinear and
quantum effects stemming from the inhomogeneous density profile. This interplay results in different dynamical regimes after an initial global quench. In particular, we show that the system may display the coexistence of markedly different dynamical domains separated by a robust interface that acts as a spatial excited-state
quantum phase transition. Furthermore, the local spinor dynamics may enter a chaotic regime characterized by irregular
evolution and exponential sensitivity to initial conditions. We map the universal phase diagram distinguishing regular and chaotic regimes, which may be probed in on-going experiments.
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All authors Jose Reyes-Calderón, Albert Gallemí, Carsten Klempt, Luis Santos
Materials Science · Cross-listed from cs.LG
Speculative Sampling For Faster Molecular Dynamics
Arthur Kosmala, Stephan Günnemann, Meng Gao et al. (+1 more)
Molecular dynamics (MD) is a key tool for simulating the dynamical behavior of atomic systems. However, MD is inherently serial, which makes it difficult to increase single-system throughput with concurrent compute. To address this, we introduce Langevin Speculative Dynamics (LSD), a distributed and model-agnostic speculative sampler for accelerating MD without adding relative error. Inspired by speculative methods in
language and
diffusion modeling, LSD uses a draft model to propose fast simulation steps and verifies them in parallel with a slower target model, applying a transport map from the draft to the target distribution. We extend speculative sampling to second-order Langevin dynamics, derive the achievable speedup as a function of physical parameters, show that LSD generalizes across different systems and draft-target combinations with a 3-9x speedup, and confirm theoretically and empirically that LSD samples trajectories from its target model distribution.
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All authors Arthur Kosmala, Stephan Günnemann, Meng Gao, Brandon Wood
Statistical Mechanics · Cross-listed from hep-th
Navid Abbasi, Xin An and Shanjin Wu
Fluctuations of conserved charges are among the main proposed signatures of the
quantum chromodynamics (QCD) critical point, but their interpretation requires a dynamical description of how fluctuation correlators evolve during the finite lifetime of the
quark–
gluon plasma (QGP) fireball. The standard baseline for this
evolution is Fickian
diffusion, in which the diffusive current follows the local density gradient instantaneously. This instantaneous-current limit can miss delayed-response effects when the current-relaxation time becomes comparable to the relaxation time of the relevant fluctuation modes. In this work we extend this baseline to Maxwell–Cattaneo
diffusion, where the current relaxes on a finite time scale and therefore retains
memory. We derive closed
evolution equations for multi-point Wigner functions and convert the freezeout correlators into acceptance-dependent cumulants along representative trajectories in the QCD phase diagram. While Fickian
diffusion already causes the correlators to lag behind their instantaneous
equilibrium values, finite current relaxation introduces an additional
memory effect beyond this diffusive lag. As a result, current
memory can suppress, shift, and reshape the non-monotonic behavior of the cumulants relative to both instantaneous
equilibrium and Fickian
diffusion, with the most visible effects appearing in higher-order cumulants and their ratios.
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Soft Condensed Matter
Anisotropic interactions induce dynamical arrest in artificial colloidal ice
Leonardo G. Alanis-Cantú and Antonio Ortiz-Ambriz
Artificial Colloidal Ice is an ice-like system used to study the effects of frustration in controlled environments where all degrees of freedom can be accessed at a length-scale large enough for optical visualization and in real time. We modify this model system by inducing anisotropic interactions through an in-plane
magnetic field. In this new regime, the system has a well-defined ground state consisting of a checkerboard pattern of fully charged vertices. However, Brownian Dynamics simulations are unable to reach this ground state and instead remain frozen in metastable disordered states, even in the absence of quenched disorder in the
lattice. This arrest is caused by the local
magnetic enhancement of the potential barrier that the particles need to cross to find a lower energy state.
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Strongly Correlated Electrons
Suppression of p-Wave Altermagnetism by Localized 4f Electrons in CeNiAsO
Jiuxiang Zhang, Yueyang Sun, Honglin Zhou et al. (+32 more)
Altermagnetism, characterized by momentum-dependent
spin splitting and zero net magnetization, has so far been explored mainly in weakly or moderately correlated d-electron systems. How
symmetry-allowed altermagnetic band splitting manifests in heavy-
fermion materials, where
magnetic exchange competes with Kondo correlations, remains unclear. Here we use high-resolution angle-resolved photoemission spectroscopy (ARPES) to investigate CeNiAsO, a Kondo-
lattice system that was predicted to be a candidate for p-wave altermagnetism.
Fermi surface mapping and polarization-dependent ARPES show that the experimentally observed itinerant bands are mainly derived from Ni 3d orbitals, while resonant photoemission reveals that the Ce 4f states remain predominantly localized with residual c-f hybridization. Ultra-low-temperature measurements reveal no resolvable near-
Fermi-level p-wave-like exchange splitting on the Ni 3d-derived conduction bands across the successive
antiferromagnetic transitions. These experimental observations cannot be captured by an itinerant-4f band-structure description, which predicts a sizable p-wave splitting in the itinerant bands. When the localized Ce 4f character is incorporated, our band structure calculations indicate that the itinerant Ce 4f band weight is shifted away from the
Fermi level and the p-wave-like splitting on the Ni 3d-derived bands is reduced to the few-meV scale. These results establish CeNiAsO as a strongly correlated f-electron setting in which the
magnetic symmetry allows p-wave-like band splitting, but localized 4f electrons strongly suppress its observable itinerant single-particle signature.
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All authors Jiuxiang Zhang, Yueyang Sun, Honglin Zhou, Jumin Shi, Di Wu, Hongze Gu, Wenjin Mao, Hengrui Dong, Yu Xu, Yinghao Li, Ziling Cao, Taimin Miao, Bo Liang, Neng Cai, Wenpei Zhu, Mingkai Xu, Jiaqi Chen, Chunhong Deng, Bo Liu, Xun Ma, Zhengtai Liu, Mao Ye, Shenjin Zhang, Zhimin Wang, Fengfeng Zhang, Feng Yang, Qinjun Peng, Zuyan Xu, Guodong Liu, Xintong Li, Hanqing Mao, Shiliang Li, Hongming Weng, Lin Zhao, X. J. Zhou
Strongly Correlated Electrons
Quenching of Nonrelativistic $p$-Wave Spin Splitting by Reduced $c\text{-}f$ Coupling in $\text{CeNiAsO}$
Xinnuo Zhang, Zhicheng Jiang, Shibo Shen et al. (+10 more)
The application of
spin-space group
symmetries to noncollinear antiferromagnets has led to the prediction of odd-parity, nonrelativistic
spin splittings, making the physical realization of a practical $p$-wave magnet a central pursuit in spintronics. The layered heavy-
fermion oxypnictide $\text{CeNiAsO}$ has been widely regarded as a prototypical platform to verify this paradigm. Here, we investigate the electronic structure of single-
crystal $\text{CeNiAsO}$ using high-resolution, ultra-low-temperature and resonant angle-resolved photoemission spectroscopy (ARPES), and $ab-initio$ calculations. Across the consecutive
magnetic transitions into the ordered phases, our spectroscopic data reveal neither the expected band folding associated with a
spin density wave nor any observable $p$-wave
spin splitting, demonstrating that the conduction bands retain full degeneracy. By tracking the temperature dependence of the Ce 4$f$ spectral weight via resonant ARPES, we find negligible $c\text{-}f$ hybridization near the
Fermi level within magnetically ordered states, confirming that the Ce 4$f$ electrons reside close to the localized limit. Our findings establish a clear many-body constraint on the projection of real-space
magnetic symmetries onto momentum-space electronic bands, demonstrating that
symmetry classifications constitute a necessary framework but are not a sufficient condition for nonrelativistic
spin splittings in the presence of strong electronic correlations.
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All authors Xinnuo Zhang, Zhicheng Jiang, Shibo Shen, Jian Yuan, Junseo Yoo, Xun Ma, Mao Ye, Jishan Liu, Zhengtai Liu, Changyoung Kim, Yanfeng Guo, Yilin Wang, Dawei Shen
Materials Science · Cross-listed from physics.chem-ph
DPA4: Pushing the Accuracy-Cost Frontier of Interatomic Potentials with EMFA SO(2) Convolution
Tiancheng Li, Wentao Li, Anyang Peng et al. (+4 more)
Machine-learning interatomic potentials now approach
quantum-mechanical accuracy, but the most expressive equivariant architectures are costly to evaluate, and the leading ones depend on auxiliary denoising or direct-force pretraining. We introduce DPA4, an SE(3)-equivariant architecture spanning six size classes from 0.48 to 25 million parameters and reaching the accuracy of the strongest published models at several-fold to an order-of-magnitude higher inference throughput. Its convolution couples edge and node features across all angular degrees in an edge-local frame, and its Wigner bilinear nonlinearity is universal in its full form and, on an exact quadrature grid, equivariant to machine precision. On Matbench Discovery, DPA4 leads every ranked metric, and every variant evaluated lies on the accuracy–throughput Pareto frontier of the compliant leaderboard. DPA4-Pro attains the lowest energy error on OMat24 and lower total-energy and force errors than the strongest conservative baseline on the OMol25 composition-validation split. All variants are trained through the conservative energy-gradient path alone, made practical by a threefold-faster compiled implementation. DPA4 thus brings leaderboard-class accuracy within the routine compute budgets of molecular-dynamics and materials-screening workflows, for both inorganic
crystals and organic molecules.
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All authors Tiancheng Li, Wentao Li, Anyang Peng, Jianming Xue, Linfeng Zhang, Duo Zhang, Han Wang
Materials Science · Cross-listed from quant-ph
Optical Stability and Photophysics of NV Centers in Diamond up to 120 GPa
Kin On Ho, Cassandra Dailledouze, Vytautas Žalandauskas et al. (+9 more)
The nitrogen vacancy (NV) center has emerged as a powerful
quantum sensor in high-pressure research, with the observation of optically detected
magnetic resonance at megabar pressures. However, some aspects of NV physics require further investigation to optimize the development of NV-based sensing under pressure. Here, we study both experimentally and theoretically the optical properties of the NV center under hydrostatic pressure. We investigate the
evolution of the zero-
phonon line (ZPL) position, radiative lifetimes, optical lineshapes, and photoionization thresholds of the NV center under pressures up to ~120 GPa. We also provide spectroscopic guidelines for performing high-pressure optical experiments. Our results confirm that the NV center remains a robust
quantum sensor under extreme hydrostatic pressures, especially for
magnetic characterization.
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All authors Kin On Ho, Cassandra Dailledouze, Vytautas Žalandauskas, Grégoire Le Caruyer, Marek Maciaszek, Claire Roussy, Marie-Pierre Adam, Martin Schmidt, Loïc Toraille, Paul Loubeyre, Lukas Razinkovas, Jean-François Roch
Statistical Mechanics · Cross-listed from hep-th
Boulder Lectures on Thermal Dynamics and Hydrodynamic EFTs
Luca V. Delacretaz
Fluctuating hydrodynamics emerges in essentially any local many-body system at nonzero temperature. Effective field theory (EFT) approaches enable the quantitative study of this emergence, providing a controlled framework to capture late-time observables. These lectures introduce the organizing principles behind
equilibrium and out-of-
equilibrium dynamics in these thermalizing systems. A central focus is the modern construction of these EFTs, which frames fluctuating hydrodynamics through the lens of "strong-to-weak" spontaneous
symmetry breaking. Drawing examples from both high-energy and condensed matter physics, we show how this paradigm adapts to systems ranging from
spin chains to relativistic
quantum field theories, including models with generalized
symmetries or
symmetries with 't Hooft anomalies. Finally, we discuss UV/IR constraints on transport parameters – viewed as the Wilson coefficients of hydrodynamic EFTs – both in continuum and on the
lattice.
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Superconductivity
Phonon-driven nodal surface superconductivity of Fermi arcs
Francesco Buccheri, Alessandro de Martino and Jeroen van den Brink
According to recent observations, the topological surface states of Weyl semimetals may develop a superconducting gap, while bulk superconductivity remains absent. What drives the formation of this novel superconducting state is an open question. Here, we show that this phenomenon can arise from the interaction of
Fermi arc electrons with both surface and bulk
phonons in time-reversal-invariant Weyl semimetals. We identify two competing pairing channels, intra-arc and inter-arc, whose relative strength is governed by the efficiency of Coulomb screening at the surface. The combined effect of the
Fermi arcs being disconnected and the weak screening of the Coulomb repulsion at the system's surface causes nodes to appear in the superconducting gap, as observed recently by photoelectron spectroscopy experiments on PtBi2. This suggests manipulation of the Coulomb screening, e.g. by a surface layer coating, as a pathway to engineer the critical temperature, as well as size and
symmetry of the surface superconducting gap.
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Materials Science
Universal theory of domain-wall width in multi-sublattice Heisenberg magnets
José M. Lendínez, Marta Yanguas, Theodor Griepe et al. (+4 more)
We propose a universal expression for the domain-wall width in generic multi-sublattice Heisenberg magnets, applicable to ferro-, antiferro-, and ferrimagnetic orders. The result follows from an exact connection between the domain-wall profile and the long-wavelength
spin-wave dispersion, yielding a unified framework for describing
magnetic textures across distinct ordering types. The predictions show excellent quantitative agreement with large-scale atomistic
spin dynamics simulations over a broad range of exchange and anisotropy values and
spin multi-sublattice structures, including three-dimensional rock-salt-type magnets and two-dimensional honeycomb and kagome ferromagnets. Moreover, we establish a general microscopic foundation for the temperature dependence of the domain-wall width. Our approach offers a powerful tool for understanding domain-wall profiles in complex
spin systems.
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All authors José M. Lendínez, Marta Yanguas, Theodor Griepe, Michael Saur, Rubén M. Otxoa, Levente Rózsa, Unai Atxitia
Materials Science
Layer-Resolved Nonlinear Optics in Finite-Thickness Two-Dimensional Systems
Liangting Ye, Chengzhi Wu, Zeyu Jiang et al. (+1 more)
Nonlinear optical (NLO) responses in two-dimensional
quantum-confined systems are typically described within bulk-based frameworks as macroscopic spatial averages. In finite-thickness van der Waals multilayers directly relevant to nanoscale devices, this picture substantially breaks down. Here, we establish a general
symmetry-based framework for classifying second-order NLO responses in multilayers. We reveal a layer-resolved organization into skin, weak-skin, and hidden effects governed by local
symmetry and stacking order. First-principles calculations for both nonmagnetic and
spin-polarized systems confirm our predictions, demonstrating that stacking alone suffices to dramatically reshape both the spatial pattern and magnitude of the NLO response, a phenomenon not explainable within standard bulk theory. Our results establish stacking geometry as an effective knob for engineering surface-selective NLO responses in layered materials.
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All authors Liangting Ye, Chengzhi Wu, Zeyu Jiang, Bing Huang
Mesoscale and Nanoscale Physics
Ferroelectric hysteresis in singly aligned graphene-hBN moiré superlattices
Bao Q. Tu, Tanweer Ahmed, Garen Avedissian et al. (+7 more)
Ferroelectric materials have the unique ability to maintain an electric polarization which can be reversed under an external applied electric field. This property makes them valuable for applications such as non-volatile random-access
memories, transducers, actuators and electro optic modulators. Recently, emergent unconventional ferroelectricity has been demonstrated in moiré superlattices of
bilayer graphene and hexagonal boron nitride (hBN) hosting non centrosymmetric stacking order. Whether this phenomenon is also present in noncentrosymmetric single layer
graphene (SLG)-hBN moiré superlattices is still under debate. Here we demonstrate a ferroelectric response in an SLG-hBN moiré superlattice. Through
Hall measurements, we pinpoint the origin of the hysteretic behavior to abnormal charge screening due to the moiré superlattice band and estimate the spontaneous polarization magnitude in the moiré superlattice structure. Temperature dependent measurements confirm that the hysteretic behavior persists from 2K up to room temperature, opening opportunities for high-mobility, ultrathin non-volatile devices
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All authors Bao Q. Tu, Tanweer Ahmed, Garen Avedissian, Suzanne Lancaster, Mayank Sharma, Kenji Watanabe, Takashi Taniguchi, Fèlix Casanova, Marco Gobbi, Luis E. Hueso
Materials Science
Neural Spectral Element Methods for stiff multiphysics PDEs with electrochemical transport benchmarks
Conrard Giresse Tetsassi Feugmo and David Pankaczy
The Neural Spectral Element Method (NSEM) evaluates each network only at fixed Legendre-Gauss-Lobatto quadrature nodes and replaces all derivative calls with precomputed spectral differentiation
matrices. The resulting deterministic loss enables limited-
memory BFGS (L-BFGS) to reach residuals of 10^-9 to 10^-10. A Kosloff-Tal-Ezer coordinate map resolves electrochemical boundary layers, while a mesh-free neural mortar framework couples multi-element domains. On the four-example Poisson-Nernst-Planck (PNP)
benchmark of Huang and co-workers, NSEM attains 10^-4 to 10^-7 relative pointwise error with two orders of magnitude fewer collocation points than the adaptive-resampling PINN baseline. Both a tanh multilayer perceptron (MLP) and a basis-aligned Legendre Kolmogorov-Arnold Network (KAN) backbone attain spectral accuracy within the same NSEM infrastructure, with the KAN requiring roughly half the Adam steps to enter the L-BFGS basin of attraction on the 1D PNP
benchmark.
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Materials Science
Surface Modification for III-V Selective Area Molecular Beam Epitaxy of Non-Selective Mask Materials
Ashlee M. García, Byron D. Aguilar, William J. Doyle et al. (+4 more)
Selective-area embedded regrowth of III-V
semiconductors by molecular beam epitaxy enables the seamless integration of metals and dielectrics into crystalline material for novel design of optoelectronic devices. However, traditional masks like $SiO_2$ and $Si_{3}N_{4}$ limit the design of high-contrast photonics in the infrared due to their high extinction coefficients at technologically relevant wavelengths. Consequently, there is a need to explore alternative mask materials to expand the selective area molecular beam epitaxy capabilities beyond those traditionally used. This study evaluates the deposition selectivity of the alternative materials $Al_{2}O_{3}$, $TiO_2$, and $HfO_2$, films with preferable spectral responses but higher surface reactivity. It was found that $Al_{2}O_{3}$ exhibits promising selective growth characteristics within typical GaAs growth temperatures, $HfO_2$ demonstrated a high non-selectivity dominated by Ga adsorption on the mask at temperatures up to 650 $^\circ$C, and $TiO_2$ proved reactive during deposition. To achieve selective growth of highly non-selective and even reactive mask materials, a surface modification technique was employed to improve the selective growth characteristics of any given film. Selective growth of $Si_{3}N_{4}$ and $TiO_2$ films was achieved with the application of a thin $SiO_2$ capping layer utilizing growth conditions typical of the GaAs/$SiO_2$ system. The relationship between the thickness of $SiO_2$ caps and growth selectivity was examined, revealing that sub-1 nm capping layers can significantly influence the mask surface chemistry, indicating that by depositing a thin layer of $SiO_2$, $SiO_2$-like selectivity for any mask material can be realized without degrading its optical response.
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All authors Ashlee M. García, Byron D. Aguilar, William J. Doyle, Pernille Undrum Fathi, Federico Capasso, Daniel Wasserman, Seth R. Bank
Materials Science
Room-Temperature Electric-Field Control of Anomalous Hall Effect in Py/BTO/LSMO Heterostructures
Kusampal Yadav, Kousik Das, Aditya Raj et al. (+7 more)
We demonstrate room temperature electric field control of the anomalous
Hall effect in epitaxial Ni80Fe20 (Py) BaTiO3 (BTO) La0.7Sr0.3MnO3 (LSMO) thin film
heterostructures grown on MgO and LaAlO3 substrates. Substrate induced strain states generate distinct
magnetic anisotropies, enabling voltage driven tuning between anomalous and topological
Hall contributions. Robust ferroelectric polarization in BTO, confirmed by piezoresponse force microscopy, couples strongly to interfacial orbital reconstruction and carrier redistribution. As a result,
Hall resistivity exhibits
giant low voltage tunability, with up to nearly 93 percent modulation at operating voltages of only 0.5 tand 2 V. Density functional theory calculations further reveal polarization controlled Rashba
spin splitting, establishing a direct link between ferroelectric order and emergent
quantum transport. These findings establish Py/BTO/LSMO
heterostructures as promising candidates for low-power multifunctional spintronic devices, where substrate engineering enables control over emergent
quantum transport phenomena.
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All authors Kusampal Yadav, Kousik Das, Aditya Raj, Mainak Ghosh, Abhishek Kumar, Kartick Biswas, Kalyan Sarkar, Pavan Nukala, Sayantika Bhowal, Devajyoti Mukherjee
Mesoscale and Nanoscale Physics
Quantized Conductance through Surface States in High Quality Three-Dimensional Dirac Semimetal Cd$_3$As$_2$ Nanowire/Nanoribbon p-n Junctions
Sungjin An, Zhuo Bin Siu, Vardan Kaladzhyan et al. (+8 more)
We report the observation of quantized conductance in high-mobility three-dimensional Dirac semimetal Cd$_3$As$_2$ nanowire and nanoribbon p-n junctions. By employing suspended device geometries with dual local gates, we form tunable p-n junctions and realize ballistic transport across sub-micron channel lengths. In a wide nanoribbon device with a channel width of $\sim 330$ nm, conductance plateaus appear at integer multiples of $2e^2/h$ in the n-n regime under high
magnetic fields. Numerical simulations suggest that these features represent unresolved
spin-split subbands due to the smaller subband spacing in wider channels, and support the interpretation that the observed quantization may originate from surface-state-dominated conduction. In contrast, narrower nanoribbons and nanowires exhibit conductance steps of $1e^2/h$, demonstrating
spin-resolved subbands likely due to enhanced confinement effects. From
spin-resolved subband spectroscopy, we extract an effective Landé $g$-factor of $\sim 43$ for the first subband in the bulk gap, establishing these nanostructures as a prospective platform for fault-tolerant
quantum electronics.
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All authors Sungjin An, Zhuo Bin Siu, Vardan Kaladzhyan, Jens H. Bardarson, Sunghun Lee, Myoung-Jae Lee, Kidong Park, Jeunghee Park, Mansoor B. A. Jalil, Jungpil Seo, Minkyung Jung
Soft Condensed Matter · Cross-listed from physics.bio-ph
Co-condensation and multivalency enable acetylation-sensitive, concentration-robust assembly of BRD4 condensates
Yury Polyachenko, Hans-Frederick Watanabe, Alexei Korolev et al. (+1 more)
Biomolecular condensates must assemble at specific locations and times inside living
cells to perform their biological functions. However, it remains unclear whether condensate formation can achieve sufficient spatiotemporal precision, responding sensitively to local chemical modifications while remaining robust to fluctuations in
protein concentration. Here we study chromatin-associated BRD4 assemblies to determine whether co-condensation with chromatin can provide the degree of discrimination required for selective targeting of highly acetylated chromatin regions. Using an ultra-coarse-grained molecular-dynamics model, we find that heterogeneous nucleation alone does not provide robust spatial discrimination, whereas co-condensation leads to spatial selectivity and rapid formation of BRD4 assemblies across a broad range of subsaturated conditions. Multivalent binding between BRD4 and acetylated histone tails sharpens the dependence of co-condensation on acetylation density through combinatorial effects, increasing discrimination between highly acetylated regions and weakly acetylated background chromatin. Together, these results show how co-condensation and multivalent binding jointly enable the sensitive, concentration-robust spatiotemporal discrimination required for selective chromatin-associated assembly.
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All authors Yury Polyachenko, Hans-Frederick Watanabe, Alexei Korolev, William M. Jacobs
Disordered Systems and Neural Networks
Probing the scale-free hierarchy of the $p=3$ spherical spin glass via persistent Langevin dynamics
Li Zhenpeng
How does a persistent random walker perceive a complex energy landscape? We address this question by studying the persistent Langevin dynamics of the p=3 spherical
spin glass, a paradigmatic mean-field model with a scale-free hierarchical landscape. By tuning the persistence time tau_p, which controls the walker's inertia and effectively sets its energy resolution delta E proportional to 1/tau_p, we measure the energy correlation time tau_corr. At temperature T=1.0, we find tau_corr scales as tau_p to the power alpha with alpha = 0.337 plus or minus 0.035 for tau_p in the range [2,32] (for N=64), in excellent agreement with the Kardar-Parisi-Zhang (KPZ) universality class prediction alpha = 1/3. Finite-size scaling using N = 16,32,48,64,128 yields the thermodynamic limit alpha(infinity) = 0.3333 plus or minus 0.0134, fully consistent with 1/3. Thus, tau_p acts as a tunable probe that reveals the predicted scale-free hierarchy of the landscape. Moreover, the temperature dependence alpha(T) for T = 0.5,1.0,1.5,2.0 exhibits a clear U-shaped curve, identifying three dynamical regimes: ballistic/inertial, KPZ, and noise-dominated. Our results establish persistent Langevin dynamics as a powerful tool for uncovering hidden landscape
topology and demonstrate that the p=3 spherical
spin glass belongs to the KPZ universality class.
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Materials Science
Sub-cycle field-driven dynamical Berry phase in solids
Lior Faeyrman, Jianing Zhang, Misha Ivanov et al. (+3 more)
In
quantum mechanics, a wavepacket acquires a
geometric phase, known as the Berry phase, as it evolves along a closed trajectory in parameter space. In condensed matter systems, the Berry phase underlies a broad range of phenomena, including the anomalous
Hall effect, orbital magnetism, and electric polarization. However, in centrosymmetric materials possessing time-reversal (TR)
symmetry, its manifestation is suppressed and effectively vanishes. When a system is driven by a strong terahertz (THz) field, it can be coherently driven far from
equilibrium, transiently reshaping its
symmetry on sub-picosecond timescales. This capability opens new avenues for
quantum control with potential applications in information processing and sensing. Here, we experimentally demonstrate that a strong THz field can transiently break inversion
symmetry in MgO, inducing a dynamical complex Berry phase, thereby manipulating the topological properties of the material. Applying high-harmonic generation (HHG) spectroscopy, we directly resolve the Berry phase, accessing both its real and imaginary components. The first is associated with coherent intraband dynamics while the second with
quantum tunneling through a potential barrier. This observation enables the reconstruction of the time-dependent
evolution of the Berry phase within the cycle of the THz field. The coherent manipulation of solids with strong fields, combined with attosecond-resolved HHG spectroscopy, represents a fundamental step toward unveiling and controlling
geometric quantum phenomena in condensed matter systems.
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All authors Lior Faeyrman, Jianing Zhang, Misha Ivanov, Liang-You Peng, Nirit Dudovich, Riccardo Piccoli
Disordered Systems and Neural Networks · Cross-listed from quant-ph
Information scrambling in all-to-all interacting models
Abhik Kumar Saha, Tanay Pathak and Masaki Tezuka
Information scrambling is a hallmark of
quantum chaos and thermalization in isolated
quantum many-body systems. We investigate scrambling dynamics in the all-to-all interacting
spin Sachdev-Ye-Kitaev (SYK)-$q$ model using both pure- and mixed-state
entanglement measures. We show that von-Neumann and Rényi
entropies exhibit rapid growth followed by saturation near Haar-random values, signaling efficient scrambling. The scrambling rate reveals a nontrivial dependence on the interaction order, system size, and
Hamiltonian scaling. We further employ mixed-state
entanglement as a powerful probe of information scrambling. We numerically find a universal relation between the Rényi-1/2 mutual information and
entanglement negativity for minimal interaction order in the early growth regime. Furthermore,
entanglement negativity displays a Page-curve-like behavior under unequal subsystem partitioning, characterized by the birth, spread, and eventual death of
quantum correlations. Our results provide a generic description of information scrambling using
entanglement dynamics in all-to-all interacting
spin systems with multi-body interactions.
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Materials Science
Moiré Strain Skyrmions in Sliding Twisted Bilayers
Rong Hu, Yu-Tao Tan, Dapeng Liu et al. (+2 more)
Strain defect is crucial to the physical properties of solid materials. Among them, strain glass induced by defect engineering provides an important paradigm for nanoscale domain manipulation. Here, we propose purely mechanical moiré strain Skyrmions, a topologically protected elastic textures whose motion can be controlled by interlayer sliding and the chirality of the moiré
bilayer. Using an empirical continuum elastic model combined with
symmetry analysis, we demonstrate the Skyrmion
lattice structure as the elastic ground state. Under interlayer sliding, these moiré strain Skyrmions exhibit the Skyrmion
Hall effect of transverse motion, with a
Hall angle determined by
bilayer chirality and inversely proportional to the moiré twist angle. Our work establishes interlayer sliding as an efficient, low-energy control knob for topological excitations, offering a new paradigm for designing
chiral-material-based information transport devices.
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All authors Rong Hu, Yu-Tao Tan, Dapeng Liu, Yizhou Liu, Jie Ren
Statistical Mechanics
Electromagnetic Field Equivalence from Moving Manifolds
David V. Svintradze
We apply a
geometric formulation of electromagnetic fields on moving
manifolds to the problem of field equivalence between dynamically separated domains. Starting from the tensorially invariant equations of motion for moving hypersurfaces, we introduce an electromagnetic specialization by constructing an energy density from the electromagnetic field tensor, yielding a
geometric extension of Maxwell electrodynamics. The classical Maxwell equations then emerge as a constrained
geometric sector of the broader
evolution system. Hence, by comparing internal and external electromagnetic configurations, we show that under isolation conditions with no interfacial current exchange, the field difference satisfies the source-free Maxwell equation. Furthermore, the
equilibrium Maxwell sector establishes a direct correspondence between the Lorentz-invariant electromagnetic structure and the geometry of constant-mean-
curvature manifolds. The resulting field-difference equations admit equivalence solutions generated by specific velocity sectors of the moving-
manifold dynamics. We further demonstrate that the resulting field-equivalence regime is intrinsically dynamical: static curved configurations generically retain nonvanishing electromagnetic contrast through curvatureinduced contributions to the
geometric pressure balance, whereas dynamically evolving
manifolds admit nontrivial admissible sectors satisfying the equivalence condition. Explicit nonvacuum realizations are obtained within the tangential-flow sector of the moving-
manifold system, while bounded static Euclidean configurations are generically excluded.
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Soft Condensed Matter
Physically-Motivated Primitive Path Analysis of Entangled Polymer Networks
B M Shahi Sifat Mottaqin, Benjamin Morrow and Robert J. Wagner
Physical entanglements between
polymer chains enhance the
moduli, strength, and toughness of elastomers and gels, yet relating
entanglement micromechanics to macroscopic mechanical benefits remains difficult. Experimentally investigating entanglements is challenging due to their nanoscale sizes, subsurface locations, and chemical indistinguishability from their surroundings. Computationally mapping structure-property relations is costly when using physics-based models that enable direct
entanglement observation, such as coarse-grained molecular dynamics (CGMD). Entanglements are also transient, configuration-dependent features without clear quantitative definitions. To address this ambiguity, we introduce an approach that quantitatively defines local entanglements along simulated
polymer backbones using the Gaussian Linking Number, and introduce a
geometric center of
entanglement verified to represent the position through which entropic chain forces are transmitted via Kremer-Grest CGMD simulations. Unlike existing approaches, which output a single linking number for chain pairs, our method identifies the multitude of load-transmitting inter- and intra-chain entanglements along a
polymer's backbone. To bridge scales, we introduce a topological
distillation algorithm that converts entangled CGMD networks into representative discrete network models (DNMs), representing entanglements as vertices and primitive paths as load-transmitting edges. Our DNMs reproduce small-strain virial stress predictions of the Kremer-Grest model with a 97% reduction in computational cost, verifying both physical accuracy and computational efficiency. This
distillation procedure will facilitate physics-based, predictive modeling of entangled network mechanics, from
polymers to architected metamaterials.
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Quantum Gases
Vibrational resonance in a one-dimensional dissipative Bose-Josephson junction
Abhik Kumar Saha
We investigate the linear and nonlinear response of a one-dimensional dissipative Bose-Josephson junction subjected simultaneously to a weak low-frequency probe and a rapidly oscillating high-frequency external drive. Starting from the dissipative two-mode Bose-Josephson equations, we derive an effective higher-order nonlinear equation for the population imbalance by retaining the leading nonlinear correction. Using time-scale separation and perturbative analysis, we obtain analytical expressions for both the linear response at the fundamental frequency and the nonlinear response at the second harmonic. We show that the high-frequency modulation modifies the effective potential landscape and dynamically breaks the
symmetry around the stationary state, giving rise to a finite second-harmonic response that is absent without the rapidly oscillating field. Both the linear and nonlinear response amplitudes exhibit resonance-like enhancement for optimal values of the high-frequency driving strength. We further analyze the dependence of the resonance characteristics on interaction strength, dissipation, and driving parameters in both the zero-phase and $\pi$-phase modes and compare the analytical predictions with direct numerical simulations. Our results demonstrate a controllable mechanism toward realizing linear and nonlinear vibrational resonance in a one-dimensional dissipative Bose-Josephson junction and open new possibilities for controlling collective dynamics in driven ultracold bosonic systems.
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Mesoscale and Nanoscale Physics · Cross-listed from quant-ph
Information Hierarchy in Many-Body Berry Phase
Kai Watanabe
Many-body
topology is a central concept in modern theories of solids, and identifying effective degrees of freedom that capture it is important both fundamentally and practically. This work studies the extent to which
geometric information of an interacting many-body ground state can be inferred from a finite number of local correlations. Starting from the Resta formula, $ z=\left\langle \exp\!\left(\frac{2\pi i}{L}\hat X\right)\right\rangle$, we view $\log z$ as the cumulant generating function and establish a generic information hierarchy across cumulant orders. We show that, for an $N$-particle system, even complete knowledge of all density correlators up to order $N-1$ does not, in general, uniquely determine the Berry phase $\gamma=\operatorname{Im}\log z \, (\mathrm{mod}\ 2\pi)$. In the thermodynamic limit, the statement becomes stronger: no finite set of local correlators suffices to determine the global holonomy. We also identify two exceptional yes-go cases in which the hierarchy is broken. First, for quasi-free models, all cumulants are determined by the particle two-point correlation function. Second,
symmetry-enforced constraints can reduce the infinite cumulant sum entering $\log z$ to finite information. The argument is analytic and does not rely on a specific microscopic
Hamiltonian. Our results clarify a limitation of approaches based on local degrees of freedom for many-body holonomy and provide a minimal framework for distinguishing when global holonomies are encoded in local correlations and when they are not. We also comment on the possibility of analogous hierarchies in other contexts, such as the
quantum marginal problem in
quantum information theory and many-body scattering problems. Finally, we discuss implications for future numerical work, including machine-learning approaches to the search for topological phases.
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Mesoscale and Nanoscale Physics · Cross-listed from physics.optics
Ultrafast internal dynamics of chiral domain walls probed by time-resolved XRMS
Dmitriy Ksenzov, Flavio Capotondi, Nicolas Jaouen et al. (+7 more)
We measure picosecond dynamics of labyrinthine stripe domains with
chiral Néel-type domain walls using time-resolved x-ray resonant
magnetic scattering (XRMS). At the stripe-domain wavevector, the helicity-summed signal shows ultrafast demagnetization, recovery, and a weak oscillatory contribution that we identify as a signature of
laser-launched coherent surface
phonons. In contrast, the dichroic signal, which is sensitive to the in-plane magnetization inside the Néel walls, shows a strong oscillatory response whose frequency decreases with increasing pump fluence. We attribute this softening to pump-induced changes in the effective anisotropy and saturation magnetization, which modify the restoring field of an internal domain-wall mode. Time-resolved XRMS thus isolates wall-specific dynamics and provides access to internal domain-wall motion in disordered stripe textures on picosecond time scales.
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All authors Dmitriy Ksenzov, Flavio Capotondi, Nicolas Jaouen, Raphael Gruber, Vincent Cros, Mathias Kläui, Matteo Pancaldi, Emanuele Pedersoli, Nicolas Reyren, Christian Gutt