Mesoscale and Nanoscale Physics
Supermoiré-trapped quadrupolar exciton
Anish Kumar, Suman Chatterjee, Kenji Watanabe et al. (+2 more)
Moiré-trapped dipolar interlayer
exciton in heterobilayers offers a rich platform to explore interaction-driven phenomena. Extending the number of layers to three and beyond leads to highly intriguing multipolar
exciton - a superposition state of vertically aligned phase-coherent
excitons. However, in experiments, unintentional twist-angle mismatch among layers may degrade the strength and homogeneity of the vertical Coulomb coupling. Here we propose that the supermoiré effect in a heterotrilayer comes to the rescue by creating periodic pockets of vertically aligned atomic registries that facilitate the formation of quadrupolar
excitons trapped in such pockets. Using WS$_2$/WSe$_2$/WS$_2$ stack, we show interaction between multiple confined levels of the top and bottom moiré interfaces, creating electric field tunable multi-level hybridized bright (symmetric) and dark (anti-symmetric) quadrupolar states. Our work underscores the critical role of supermoiré effect in quadrupolar
excitons. The discovery of reduced sensitivity on precise angle-
alignment will ignite exploration of complex excitonic states in multi-layered
heterostructures.
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All authors Anish Kumar, Suman Chatterjee, Kenji Watanabe, Takashi Taniguchi, Kausik Majumdar
Statistical Mechanics
Extreme First-Passage Time of Many Interacting Particles
Ruicheng Bao
Extreme first-passage events are broadly relevant to biological, chemical, and physical processes in which the first successful arrival determines the outcome. Existing theories are largely confined to noninteracting searchers. Interacting extreme-statistics problems are notoriously difficult because correlations destroy probability factorization. We establish a general framework for interacting extreme search. A no-go
theorem shows that broad classes of short-range interactions cannot beat the $1/\ln N$ extreme timescale of $N$ independent Brownian searchers, and complementary upper bounds prove that this scale is exact for repulsive interactions. We then identify three sharp mechanisms beyond the logarithmic class and derive a unified interaction-driven acceleration limit. In particular, deterministic pairwise interaction can at most reduce the extreme search time to order $1/N$, while
stochastic pairwise forcing attains $1/(N\ln N)$. Our results separate acceleration due to statistical redundancy from that generated by coherent many-body transport or amplified fluctuations, deepening our understanding of interacting many-body systems.
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Statistical Mechanics
Effective field theories of nonlinear fluctuating hydrodynamics in one dimension
Matija Koterle and Enej Ilievski
Describing emergent macroscopic phenomena in low spatial dimensions is known to be notoriously challenging, primarily due to strong interactions that render perturbative approaches inapplicable. On the other hand, low-dimensional systems host a wealth of unorthodox phenomena. A prominent example is the emergence of superdiffusive transport in one-dimensional interacting systems, traditionally studied in the framework of nonlinear fluctuating hydrodynamics. After identifying and discussing internal inconsistencies in the previous formulations, in this work we develop a general and systematic approach for constructing effective field theories of one-dimensional hydrodynamic systems in the form of coupled
stochastic Langevin-type equations compatible with the physical requirements of local
equilibrium states such as the thermodynamic Maxwell relation and fluctuation-dissipation
symmetry. We implemented a general numerical integration scheme and exemplified our construction on a simple model of two interacting hydrodynamic modes with a non-Gaussian stationary
equilibrium measure.
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Strongly Correlated Electrons
Exact Neural-Network Representations of the Motzkin States
Runde Zha, Yuntian Gu, Chaohui Fan et al. (+3 more)
Motzkin
spin chains are paradigmatic frustration-free one-dimensional
quantum systems whose ground states feature exactly solvable combinatorial structures and exotic, area-law-violating
entanglement scaling. Specifically, colorless Motzkin states exhibit critical logarithmic
entanglement divergence \(\log N\) with system size \(N\), while their colorful counterparts host supercritical sublinear \(\sqrt{N}\)
entanglement growth. Such unconventional
entanglement behaviors place these states well beyond the expressive capability of standard
matrix product states, which are fundamentally constrained by the
entanglement area law. Here, we systematically construct exact, training-free neural-network representations for both colorless and colorful Motzkin states across four mainstream architectures, including recurrent, feedforward, convolutional, and
transformer networks. Our core design leverages a causal prefix-sum module, implementable via recurrent updates, feedforward mappings, or masked
attention layers, combined with position-selective rectified linear gates that enforce the Motzkin height constraints. For the colorful states, we further introduce a dedicated causal stack module that explicitly encodes the last-in-first-out color-matching rule. Our results demonstrate that neural architectures can accurately capture highly non-trivial
entanglement features inaccessible to conventional tensor networks, providing prototypic examples for benchmarking and a constructive design framework for future neural-network
quantum state developments targeting strongly entangled
quantum systems.
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All authors Runde Zha, Yuntian Gu, Chaohui Fan, Jia-lin Chen, Hai-Jun Liao, Tao Xiang
Materials Science
Machine Learning Inference Limits of Routine Cement Characterization for CEM I Performance: Evidence From a Multi-Producer Dataset
Marchellino Ghorayeb, Christiane Rößler, Horst-Michael Ludwig et al. (+2 more)
Routine cement performance characterization provides continuous quality control data, but its information content for performance inference and transferability across independent producers remains uncertain. This study analyzes 476 cement records from 23 European producers, collected in one laboratory over 27 years, to determine what can be inferred from routine measurements. The analysis focuses on CEM I and combines
oxide chemistry, Blaine fineness, particle-size distribution descriptors, physical properties, and derived Bogue and equivalent-alkali descriptors with machine learning attribution and producer-transfer tests. For CEM I, fineness is the strongest descriptor family for strength class and water demand, but
oxide chemistry contributes a comparable signal when evaluated jointly. Blaine and compact particle-size distribution representations are largely interchangeable within the descriptor space, indicating that the dominant recoverable fineness information is captured by routine measurements. Equivalent alkali shows a consistent negative association with 28-day strength, through K$_2$O in this
dataset. Strength class and water demand can be recovered from routine cement characterization data. The early-strength designation is recovered only as a population-level tendency, not a physically separable class, because early-strength development can arise from combinations of fineness, sulfate–alkali chemistry, phase assemblage, and plant practice. Producer-holdout tests show that absolute prediction errors remain comparable across the held-out producers in this
dataset, whereas recovery of within-producer strength variation is producer-dependent. Routine CEM I characterization therefore supports useful performance inference across producers, while exposing producer-specific variation whose recovery may require additional speciation.
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All authors Marchellino Ghorayeb, Christiane Rößler, Horst-Michael Ludwig, Leon Herrmann, Stefan Kollmannsberger
Statistical Mechanics · Cross-listed from quant-ph
Quantum many-body scars with tunable entanglement and Hamiltonian inverse design from ZX-calculus
Marcin Szyniszewski
Diagrammatic
languages such as ZX-calculus provide compact and intuitive descriptions of
quantum processes and have become established tools for
circuit simplification, verification, and compilation. However, their potential as a framework for constructing many-body states and the
Hamiltonians that host them remains largely unexplored. Here, we introduce families of fractal many-body states obtained from ZX-diagrams based on the Sierpiński triangle and Sierpiński carpet. By construction, the underlying graph connectivity imposes atypical subvolume-law minimum-cut upper bounds on
entanglement: at most logarithmic scaling for the triangle family and sublinear power-law for the carpet family. By adjusting the free parameters of the ZX-diagram construction, we can tune the actual
entanglement scaling: we demonstrate both area-law and logarithmic scaling for the triangle, and both log law and power-law for the carpet. Additionally, their local observables retain fractal-like spatial structure, identifying these states as natural candidates for atypical eigenstates in otherwise thermalizing systems. For the triangle family, we combine parent-
Hamiltonian methods, insights from ZX-calculus, and local ZX identities that certify exact annihilation of the target state, producing frustration-free
Hamiltonians whose terms admit simple representations in the same diagrammatic
language as the states themselves. We then construct a local deformation that produces chaotic level statistics while
embedding the fractal ZX state in the bulk of the energy spectrum as an exact
quantum many-body scar. Our results demonstrate, through this explicit construction, that ZX-calculus can serve as a framework for
Hamiltonian inverse design, in which
quantum many-body scars, their local annihilators, and the chaotic
Hamiltonians embedding them can be constructed and related through a set of graphical identities.
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Strongly Correlated Electrons
Exactness of Symmetry-Broken Self-Interaction Correction in the Strongly-Correlated or Classical Limit: Harmonium as a Demonstration
Cody Woods, Yunzhi Li, Wenqing Yao et al. (+2 more)
Strong electron correlation is an important challenge to both wavefunction and density functional theory. It has been argued that the Perdew-Zunger 1981 self-interaction correction to any density functional approximation, after
symmetry breaking, can correctly describe the ground-state energy in the strongly-correlated limit in which each electron is described by a highly-localized and non-overlapped one-electron
spin orbital. It has also been argued that the classical limit, in which Planck's constant tends to zero, is the strongly-correlated limit of
quantum mechanics, where standard density functionals fail badly, as demonstrated by the exactly-solvable problem of harmonium (two Coulomb-interacting electrons bound by a spherically-symmetric harmonic-oscillator external potential). Here we combine these two ideas and demonstrate that, for harmonium,
symmetry-broken self-interaction correction is exact in the limit where Planck's constant tends to zero, and usefully accurate for all values between 0 and the physical value (1 in atomic units). We also show that the Planck-constant-dependent symmetric ground-state density can be restored by spherical averaging of the broken-
symmetry density.
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All authors Cody Woods, Yunzhi Li, Wenqing Yao, Chen Li, John Perdew
Strongly Correlated Electrons
Quasiparticle interference as a tool to study quantum materials
Luke C. Rhodes, Yuhki Kohsaka, Tetsuo Hanaguri et al. (+2 more)
To understand the properties of
quantum materials a detailed knowledge of the material's low energy electronic structure is key. Details of the electronic structure drive the ground state through electronic instabilities, electronic correlation effects, new electronic orders or just the absence of electronic states near the
Fermi energy - making a realistic and detailed understanding crucial to be able to control and design properties of
quantum materials. The past 25 years have seen a significant improvement in experimental techniques to observe the true electronic structure, in particular in techniques such as Angle resolved photoemission spectroscopy (ARPES) where energy resolutions of 2meV are routinely achievable now, which however is limited to zero
magnetic field and only provides information about the occupied states. Scanning tunneling microscopy (STM) achieves a significantly better energy resolution <100${\mu}$eV and can operate at temperatures well below 50mK and in
magnetic fields. While per se a real-space technique, by imaging quasiparticle interference (QPI) STM can also provide information about the electronic structure. This technique has been used over the past decades to study a wide range of
quantum materials to understand correlated electron behaviour. Recent theoretical progress now enables routine modelling of QPI, a key requirement to interpret the complex data. Here, we review the principles of QPI, its origin, experimental detection, and the physical insight gained from the study of QPI and possible future directions for this technique.
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All authors Luke C. Rhodes, Yuhki Kohsaka, Tetsuo Hanaguri, Carolina de Almeida Marques, Peter Wahl
Materials Science
Reversible photo-switching optical functionality in two-dimensional mixed-halide hybrid perovskites
Enamul Haque, Wenxin Mao and Javier Cerrillo
Ion migration in halide perovskites is often associated with defects, irreversible processes, and structural instability, making them largely impractical for photo-switching applications. Here, we demonstrate a physical mechanism for reversible, defect-free light-induced halide-ion swapping in two-dimensional mixed-halide perovskites. We find that the halide-ion swapping process arises from strong light-
lattice coupling rather than defects. By combining nudged elastic band and photo-force calculations, we show that photo-induced forces perform non-
equilibrium work that drives halide ions along the halide-exchange path without reaching the fully swapped configuration. Thus, the cumulative light-induced work can only partially overcome the ground-state activation energy barrier in the presence of light. Analysis of
lattice dynamics identifies a few soft
phonon modes, two of which are IR-active with oscillator strength $\approx -0.14$ e/(amu)$^{1/2}$, which may be considered the microscopic origin of light-induced halide-ion swapping. This microscopic origin is further supported by band-edge-selective electron-
phonon coupling, which amplifies interactions among excited carriers under illumination and with halide-ion motion without inducing a uniform dynamical instability. Using GW (G-Green's function and W-screened Coulomb interaction) calculations, we accurately reproduce the experimentally observed optical absorption spectra in the absence of light, enabling us to describe the light-induced excited state reliably. We demonstrate a clear
redshift in the optical spectra in the presence of light, which is due to light-induced bandgap renormalization. Overall, these findings not only establish an intrinsic, defect-free mechanism for photoswitchable optical functionality in 2D mixed-halide perovskites but also demonstrate an intrinsic self-resetting feature in the absence of light.
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Soft Condensed Matter
Effects of long-chain branching, short-chain branching, and polydispersity on pressure sensitive rheology of polymer melts
Lilian Lin, Matthew Joe and Heon E. Park
The rheological behavior of
polymer melts under high pressure is a critical factor in many industrial processes like injection molding and extrusion, yet it is often inadequately characterized. At operating pressures that can exceed 100 MPa, viscosity can increase by orders of magnitude, making atmospheric-pressure data insufficient for accurate process simulation. This pressure induced viscosity increase is highly dependent on molecular architectures of the materials. This study aims to deconstruct the influence of specific structural features such as short-chain branching (SCB), long-chain branching (LCB), and polydispersity on the pressure sensitivity of the viscosity of polyethylene. Utilizing a high-pressure sliding plate rheometer (HPSPR) to ensure accurate measurements under uniform shear and pressure, we characterized four distinct polyethylene melts. All samples, regardless of their structure, exhibited piezorheologically simple behavior, allowing the application of time-pressure superposition over the entire shear rate range. A key finding is that the long-chain branched sample, known from the literature to be thermorheologically complex, was found to be piezorheologically simple. This dichotomy is explained by the different physical mechanisms of temperature and pressure. The pressure sensitivity of the viscosity, quantified by the pressure-viscosity coefficient, was found to be strongly dependent on molecular branching. Both SCB and LCB significantly increase the pressure sensitivity while polydispersity had a negligible effect. These results demonstrate that molecular branches are the dominant structural parameter controlling the rheological response of polyethylene to pressure, providing crucial insights for the development of more accurate predictive models for high-pressure
polymer processing.
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Soft Condensed Matter
Pulsatile poromechanics in layered soft media controls fluid flow and solute transport: from fundamentals to brain clearance
Matilde Fiori and Sylvie Lorthois
Soft porous media often feature a heterogeneous structure. Notably, biological tissues - such as cartilage and the
brain tissue - consist of two or more layers, with varying mechanical and fluid-flow properties. Despite the ubiquity of periodic loading in these systems, the physical implications of layering on nonlinear poromechanics and solute transport remain poorly understood. Uncovering these coupled mechanisms could clarify the fundamental physics behind pressing topics, such as
brain metabolic clearance. Here, we address this gap using a
bilayer model of a generic soft porous medium. To isolate the specific role of layering, we select combinations of material properties (porosity, permeability, and p-wave modulus) that maintain an identical poroelastic timescale, $T_{\mathrm{PE}}$, across four layered configurations and a reference homogeneous case. We demonstrate that while $T_\mathrm{PE}$ is the key parameter governing the response in a homogeneous medium, the same $T_\mathrm{PE}$ leads to non-trivial localization/propagation patterns for strain, fluid flow and solute transport in a
bilayer medium. These non-intuitive results suggest that layered architectures may provide functional benefits for cellular homeostasis over homogeneous ones. Finally, we show that pathological alterations to the
brain's layered structure significantly disrupt fluid-flow and metabolic waste clearance, offering a possible mechanical explanation for impaired transport in disease.
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Statistical Mechanics · Cross-listed from hep-th
Entanglement in Presence of Topological Interfaces and Dualities
Christian Northe, Riccardo Poletti and Paolo Rossi
Entanglement through interfaces has attracted considerable
attention in 2d conformal field theory (CFT). However, it is known that field-theoretic predictions based on the existing framework are in general incompatible with numerical results [1-4]. A new framework for
entanglement through topological defects was recently proposed in [5]. It provides a general description of
entanglement through topological defects and successfully reproduces the numerical results for the Ising model in all tested cases and regimes. The key insight is that the relevant
quantum correlations are encoded in twisted states, allowing for the construction of the full reduced density
matrix (RDM). In this work we pursue two objectives. First, we provide new examples by studying defects in the free
boson CFT. Second, we extend the framework to topological interfaces connecting two, possibly distinct, CFTs. Of particular interest are interfaces relating dual theories. We show that the reduced density
matrix for a duality interface is the projection of the
vacuum reduced density
matrix onto a single
symmetry sector, closely paralleling the framework of
symmetry resolution. Unlike
symmetry resolution, however, the projection is imposed by the physical interface itself, demonstrating that duality interfaces reflect
quantum correlations back into the entangling interval. We establish this mechanism for diagonal and non-diagonal rational CFTs as well as the free
boson CFT. Relative
entropy allows us to quantify the distinguishability of the duality interface RDM from the
vacuum RDM.
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Soft Condensed Matter · Cross-listed from physics.comp-ph
Hyperspatial Sampling: Circumventing Free-Energy Barriers via Replica Exchange with Extra Dimensions
Henrik Christiansen, Matheus Ferraz, Takashi Maruyama et al. (+1 more)
Simulating systems with rugged free-energy landscapes remains a central challenge in computational physics and chemistry. We introduce hyperspatial replica exchange (HS-REX), an enhanced sampling method in which the physical system is artificially extended by additional spatial dimensions. In higher dimensions, free-energy barriers can be circumvented through paths that are geometrically inaccessible in the original space. Restricting the penalty to only solute atoms dramatically reduces the number of replicas required for solvated systems compared to standard temperature replica exchange, a feature especially relevant for biological applications. As proof of concept, we demonstrate the method on a double-well model system and on alanine dipeptide in explicit water as
benchmark system. In the latter case, HS-REX achieves enhanced conformational sampling of not only the slow backbone dihedral angles, but also both
chiral configurations of the molecule, which are sterically inaccessible to standard sampling in three dimensions. This demonstrates enhanced ergodic sampling over conventional temperature replica exchange.
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All authors Henrik Christiansen, Matheus Ferraz, Takashi Maruyama, Francesco Alesiani
Statistical Mechanics · Cross-listed from hep-ph
Non-Markovian heavy-quark equilibration and equilibrium correlation function in a thermal medium
Monisha Nair, Juan Torres-Rincon and Santosh K. Das
We compute the charm-
quark current-current correlation function within the Langevin framework and extract the heavy-
quark diffusion coefficient using the Green–Kubo formula. The formalism is further extended to evaluate the correlation function using a generalized Langevin equation that incorporates
memory effects via an exponentially decaying
memory kernel. We find that while
memory effects qualitatively modify the transient structure of the current correlations, the value of the transport coefficient remains unchanged in the non-relativistic limit. In addition, we investigate heavy-
quark thermalization in the presence of
memory and compare the non-
equilibrium solution of a generalized Fokker–Planck equation with the one obtained from the generalized Langevin equation in the non-relativistic limit. We also consider the relativistic version of the correlated noise case and observe that
memory effects can give rise to a damped, oscillatory equilibration of the heavy
quark in a non-Markovian bath.
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Disordered Systems and Neural Networks · Cross-listed from quant-ph
Quantum-informed surrogate sampling for combinatorial optimization
Elisabeth Wybo and Jernej Rudi Finžgar
We introduce
Quantum-Informed Surrogate Sampling (QISS), a post-processing framework that generates candidate solutions to combinatorial optimization problems from low-weight correlations of shallow
quantum circuits. The
quantum device estimates local observables, which are directly accessible by repeated measurements and for which a wide range of error-mitigation tools are available, while candidate solutions are generated classically without explicit dependence on the combinatorial optimization problem itself. We evaluate QISS on Maximum Cut and Maximum Independent Set problems on $N$ variables and show that only $O(N)$ low-order correlators from shallow
circuits suffice to produce competitive solutions that surpass vanilla QAOA. For MaxCut on 3-regular graphs, QISS from $p=3$ QAOA correlators outperforms vanilla QAOA at $p=17$ on average, with further improvements possible by warm-starting QAOA. We validate the procedure on the 54-
qubit IQM Emerald
quantum device and demonstrate its noise resilience. Our results support a regime for near-term optimization in which shallow
circuits serve not as direct samplers but as generators of informative statistics for scalable classical sampling.
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Materials Science
Mechanisms of Microstructural Evolution and Degradation in Aluminum under High-Damage Irradiation
Alhassan S. Issaka, Sadie Wicks, Vishal Yadav et al. (+3 more)
Aluminum
alloys are widely used in research reactor systems, yet the mechanisms governing irradiation-induced degradation remain poorly understood. Here we combine conventional cascade-overlap molecular dynamics simulations with an accelerated Iterative Kinetic Approach (IKA) to investigate defect
evolution in single-
crystal Al subjected to 50 keV He irradiation. Benchmarking shows that IKA reproduces the essential defect kinetics of cascade simulations while enabling access to substantially higher accumulated damage. By extending the IKA to higher damage levels, we identified three distinct regimes governing radiation-induced degradation in Al: recombination-driven annihilation, defect accumulation, and sink-controlled absorption. At higher damage, Frank loops dissociate into Shockley partials and stair-rod loops, ultimately driving the nucleation and growth of stacking-fault tetrahedra (SFTs). These transformations progressively convert mobile defects into SFTs. Ultimately, the synergistic effect of interstitial and vacancy loops and SFTs increases irradiation hardening in Al at 300 K. This work provides insight into irradiation-induced degradation in aluminum reactor materials.
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All authors Alhassan S. Issaka, Sadie Wicks, Vishal Yadav, Assel Aitkaliyeva, Michael R. Tonks, Simon R. Phillpot
Materials Science
Magnetic proximity-induced non-relativistic valley polarization
Weifeng Xie, Yongqi Chen, Yiboyang Sun et al. (+3 more)
The
magnetic proximity effect in van der Waals (vdW)
heterostructures exerts a significant impact on the electronic and
magnetic properties of adjacent materials. Here, we propose vdW
heterostructures composed of monolayers ferromagnets (FM) and altermagnets (AM), in which the
magnetic proximity effect from the FM induces pronounced non-relativistic valley polarization in the AM. Furthermore, by flipping the magnetization of the FM and the direction of Néel vector of the AM, four independent valley-polarized states can be realized in the FM/AM vdW
heterostructures, exhibiting strong magneto-valley coupling. The phenomenon is qualitatively elucidated by a tight-binding model and demonstrated to be generalizable. These findings suggest that FM/AM vdW
heterostructures hold potential application in the field of valleytronics-based information storage.
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All authors Weifeng Xie, Yongqi Chen, Yiboyang Sun, Xiong Xu, Yunliang Yue, Hui Wang
Materials Science
Charge-Density-Wave Phase Transitions in Monolayer 1T-TaS2 from Universal Machine Learning Molecular Dynamics
Valentina Nesterova, Tribhuwan Pandey, Tom Berlijn et al. (+3 more)
Charge-density-wave (CDW) phases in 1T transition-metal dichalcogenides arise from strong electron-
phonon coupling and accompanying
lattice instabilities. Capturing their temperature-dependent structural
evolution using conventional first-principles molecular dynamics (MD) remains challenging because of the large supercells and extensive finite-temperature sampling required. Here, we combine density functional theory (DFT), universal machine-learning interatomic potentials (MLIPs), MD, and temperature-dependent effective potential
phonon calculations to investigate the structural and vibrational signatures of CDW transitions in monolayer 1T-TaS2. Benchmarking against DFT displacement energies identifies UMA-s-1p1 universal machine learning potentials with sufficient accuracy for subsequent finite-temperature simulations. Our results show that large-scale MD simulations reproduce the experimentally observed phase transition sequence from the low-temperature
Star-of-David (SoD) distorted structure to the high-temperature primitive hexagonal structure, as quantified by the number of Ta atoms attributed to SoDs. Heating-cooling cycles exhibit thermal hysteresis, and upon cooling, the system freezes into a multi-domain state in which {\alpha} and e̱ta} CDW chiralities nucleate independently and persist to the lowest temperatures. These findings demonstrate that carefully benchmarked universal MLIPs can provide a scalable framework for finite-temperature studies of CDW materials.
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All authors Valentina Nesterova, Tribhuwan Pandey, Tom Berlijn, Fariborz Kargar, Lucas Lindsay, Konstantin Klyukin
Materials Science
Hidden Truchet Architecture in Zinc $p$-Hydroxybenzoate
Hunter J. Windsor, Guy Greenbaum, Tristan N. Dolling et al. (+2 more)
We redetermine the structure of the disordered metal-organic framework Zn(hba) (hba$^{2-}$ = the dianion of 4-hydroxybenzoic acid). Using single-
crystal X-ray diffraction measurements, we characterise the structured diffuse scattering that is experimentally observed for this material and which is characteristic of strongly correlated disorder. We use
geometric and
crystal chemical arguments to propose a general model for correlated disorder in Zn(hba), and then relate this model to a specific realisation of so-called Truchet tilings. Using Monte Carlo simulations, we proceed to show that the model so developed is simultaneously consistent with both the average
crystal structure solution described previously, and the structured diffuse scattering reported here. The existence of ordered analogues with different, but related, chemistry suggests scope for control over correlated disorder in this family of metal-organic frameworks. Our study illustrates the potential for a Truchet-tile formalism to help describe and understand more generally the correlated disorder that occurs in framework materials - even amongst those that are chemically and crystallographically dissimilar.
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All authors Hunter J. Windsor, Guy Greenbaum, Tristan N. Dolling, Yevheniia Kholina, Andrew L. Goodwin
Strongly Correlated Electrons
Unconventional $\mathbb{Z}_2\times\mathbb{Z}_2\times\mathbb{Z}_2$ topological order in the kagome XY toric code
C. Kölbl, M. Vieweg and K.P. Schmidt
We investigate the
quantum phase diagram of the XY toric code (XYTC) on the kagome
lattice consisting of $XY$ hexagonal and triangular plaquette operators and conserved
star operators. We demonstrate analytically by exploiting an exact local $\mathbb{Z}_2$-
symmetry on dodecagons that the kagome XYTC realizes a $\mathbb{Z}_2\times\mathbb{Z}_2\times\mathbb{Z}_2$ topologically ordered phase in the limit of large hexagonal \mbox{plaquette} operators. This unconventional topological phase involves 64 quasi-particles - Abelian anyons - with restricted mobility on three colored sublattices establishing a
quantum dimension of eight. The large number of topological superselection sectors originates from six independent Wilson loop operators, acting as emergent one-form
symmetries. The resulting anyon structure is richer than that of established topological codes like the toric and the color code. A corresponding CSS topological stabilizer code is formulated, opening novel possibilities for the encoding and manipulation of topological
quantum information.
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Materials Science
Substrate-metal interface engineering enhances TaN/Ta thin film superconducting resonator performance
Moritz Singer, Harsh Gupta, Benedikt Schoof et al. (+6 more)
Tantalum has been demonstrated as a promising material for superconducting
qubits. However, comparatively little
attention has been given to its nitrides. Tantalum nitride exhibits a range of stoichiometries, resulting in a variety of material properties, including both superconducting and non-superconducting phases. Owing to this versatility, tantalum nitrides can serve multiple purposes in superconducting
qubits: as seed layers for alpha-Ta growth, as a superconducting base material and as a non-superconducting barrier in the Josephson junction. In this study, we explore the performance of superconducting TaN and Ta thin film combinations on silicon substrates in terms of internal quality factor Qi. We find that standalone TaN films exhibit Qi values of about 1.5x10^5 at 100mK in the single-
photon regime. Surprisingly, a resonator made from Ta grown on a few-nanometers-thick TaN seed layer yields largely the same performance. However, adding an additional, few-nanometers-thick Ta buffer layer between the Si substrate and this TaN seed layer enhances Qi significantly up to 5.9x10^5. Supporting transmission electron microscopy measurements reveal nitrogen accumulation and structural disorder at the TaN-Si interface, while this interfacial modification is suppressed when the Ta buffer layer is introduced. The observed improvement in resonator performance is consistent with a reduction of interface-related two-level system losses and strongly supports the hypothesis that controlling the substrate-metal interface is pivotal for the performance of superconducting
qubit circuitry.
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All authors Moritz Singer, Harsh Gupta, Benedikt Schoof, Elena Willinger, Anton Orekhov, Alexandra Schewski, Samuil Kostadinov, Philip Constantin Schneider, Marc Tornow
Quantum Gases
Understanding interaction-driven transport in flux lattices with evolution-path symmetry
Jian-Song Pan, Xiaofan Zhou and Wei Yi
The destruction of Aharonov-Bohm (AB) caging by interaction and the emergence of interaction-induced
chiral currents in flux
lattices are two paradigmatic examples of interaction-driven
quantum transport. While various mechanisms, such as bound-state formation and
chiral spectral imbalance, have been proposed, a unifying physical picture remains elusive. Here, we employ the concept of
evolution-path
symmetry (EPS) and its interaction-induced breaking as a framework to understand interaction-induced delocalization in flux
lattices. EPS is defined as the invariance of a path's contribution under combined
geometric and phase transformations. We demonstrate that in a $\pi$-flux rhombic
lattice, interactions break the EPS present in the non-interacting limit by modifying the phase accumulation of many-body paths, thereby lifting the destructive interference responsible for AB caging. Furthermore, we apply this framework to explain interaction-induced
chiral transport in flux ladders, where interactions break the phase relationship between symmetric paths, leading to a non-vanishing
chiral current. Our work establishes EPS as a powerful tool for understanding transport phenomena beyond conventional eigenstate analysis.
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Strongly Correlated Electrons
When Can a Cavity Move a Mott Transition? A Spectral-Density Criterion within Gutzwiller Theory
Nikhil Vamsodharakan Seshadri and Yu Zhang
Can
vacuum electromagnetic fluctuations shift a bulk Mott transition? Within the Gutzwiller variational method, we derive a criterion that separates collective spectroscopic hybridization from thermodynamic phase control. We show that a Mott transition shifts only when the electromagnetic environment supplies finite thermodynamic spectral weight with bond-scale variation. A joint frequency–spatial Pauli–Fierz density gives the leading shift. Surface
phonon polaritons yield a $d^{-3}$-to-$d^{-5}$ crossover, while finite-coordination variational Monte Carlo supports the predicted critical coefficient and $M/N$ scaling.
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Materials Science
Unbiased Diffusion Monte Carlo for non local operators
Carlos Rodriguez Perez, Valerio Olevano, Francesco Sottile et al. (+1 more)
We propose a new mathematically exact method for computing unbiased
Diffusion Monte Carlo (DMC) estimates of non-local operators. We demonstrate that the current state-of- the-art technique, Forward Walking, is only exact for local quantities and fails to yield unbiased results for the non-local components of reduced density
matrices (RDMs). Our method significantly outperforms Forward Walking, as shown in two systems: in the symmetric Hubbard dimer it yields a pure 1RDM; while in the Helium atom it will give an unbiased 1RDM in the limits of zero time step and infinite walkers.
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All authors Carlos Rodriguez Perez, Valerio Olevano, Francesco Sottile, Vitaly Gorelov
Materials Science
SAGE-Net: Semantics-Augmented Geometric Encoder for Material Property Prediction
Guanghui Zhang, Yuxuan Yao, Kieran B. Spooner et al. (+4 more)
Reliable structure-property modeling is crucial for accelerating materials discovery, where
crystal graphs and structure-derived crystallographic descriptions provide complementary
geometric and semantic information. Existing
multimodal materials models primarily incorporate textual information through post-encoding fusion, latent-space
alignment, or
attention-based representation interaction mechanisms. However, in most cases, crystallographic semantics are introduced after structural encoding and therefore cannot directly guide the formation of atom-level
crystal-graph representations. Here, we present Semantics-Augmented
Geometric Encoder Network (SAGE-Net), a flexible
multimodal framework that injects description-derived chemical and crystallographic semantics into
geometric message passing. SAGE-Net introduces Semantic-Guided Message Passing (SGMP), which gates atom-level updates and enables crystallographic semantics to directly modulate local
geometric interactions across multiple graph neural network (GNN) backbones. Across
benchmarks covering bandgap, mechanical, transport-related properties, and synthesizability assessment, the SAGE-Net instantiated with different GNN backbones achieves the lowest MAE on eight out of ten JARVIS-DFT regression targets and delivers strong or highly competitive performance against both structure-based and
multimodal baselines. For synthesizability assessment, the SAGE-Net demonstrate outstanding classification performance and high recall rates. Interpretability analysis unravels that SAGE-Net effectively captures physically interpretable crystallographic features, viz. space group, dimensionality, polyhedral environments, among others. Together, these results demonstrate SGMP-based SAGE-Net as a general and transferable framework for deeply integrated
multimodal materials learning.
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All authors Guanghui Zhang, Yuxuan Yao, Kieran B. Spooner, Jun Yin, Dan Han, David O. Scanlon, Lijun Zhang
Materials Science
Composition Anisotropy Drives Large Bulk Photovoltaic Fields Along the Non-polar Vertical Direction in 2D Hybrid Perovskite Ferroelectrics
Yuzhong Hu, Andrii Shcherbakov, Jonathan Zerhoch et al. (+7 more)
The photovoltaic electric field of the bulk photovoltaic effect (BPE) reflects the intrinsic ability of ferroelectrics to separate photoexcited
excitons into electrons and holes, and are essential parameters for applications such as voltage-readout photodetectors. Because polarization defines the cation-anion displacement and noncentrosymmetric axis, the polar direction is generally one of the orientations exhibiting strong bulk photovoltaic field (EBPE). Here, we report emergent BPE behavior in 2D hybrid perovskite ferroelectrics (HPFs), where EBPE can be two orders of magnitude higher along the vertical nonpolar direction than along the polar in-plane direction. Its magnitude is up to orders of magnitude higher than that of
benchmark photoferroelectrics across different material systems and is the highest among 2D HPFs reported so far. This strong BPE response with emergent directional anisotropy originates from the unique coupling among the shift-current BPE mechanism, an efficient photocarrier-generating inorganic part, and an
insulator-like organic part, a combination that is conflicting or inaccessible in traditional photoferroelectrics. This composition and anisotropy also produce basic BPE behavior distinct from that of typical photoferroelectrics, including a
laser intensity dependent photovoltage and a nonlinear scaling of photovoltage with material dimension. We analyze and develop a series of formulas to describe the emergent photovoltage phenomena, which should be applicable to this novel 2D ferroelectrics family and to polar systems with similar anisotropy and robust photoelectric response.
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All authors Yuzhong Hu, Andrii Shcherbakov, Jonathan Zerhoch, Lars Schneider, Shangpu Liu, Xitao Liu, Fangping Zhuo, Lovro Fulanovic, Felix Deschler, Martijn Kemerink
Materials Science · Cross-listed from physics.optics
Counterdirectional Exciton and Trion Motion in Applied Electric Field
Daniel Vaz, Yuanjun Guan, Qiaochu Wan et al. (+13 more)
Charged excitonic complexes are central to the optoelectronic and many-body properties of
semiconductors, yet their real-space transport dynamics remain largely unexplored. Here, we report the direct optical observation of trion motion under an applied electric field. The trions exhibit electrically driven drift with velocities approaching {$10^5~\mathrm{m/s}$}. Unexpectedly, the trion flow induces a pronounced back-action on coexisting neutral
excitons, driving them in the opposite direction and giving rise to counterpropagating
exciton-trion transport. Our results reveal an interaction-driven nonequilibrium transport regime of mixed excitonic fluids and establish a direct route for imaging the dynamics of more complex charged quasiparticles, including doubly charged
excitons.
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All authors Daniel Vaz, Yuanjun Guan, Qiaochu Wan, Bobby Bobby, Anshul Ramavath, Brandon Vargo, Juntong Ye, Jonathan Beaumariage, Om Patel, Kenji Watanabe, Takashi Taniguchi, Xiong Feng, James Hone, Nathan Youngblood, Zheng Sun, David W. Snoke
Strongly Correlated Electrons
Mizuki Urai, Hiraku Saito, Daisuke Nishio-Hamane et al. (+2 more)
We investigated the zero-field
magnetic structure of the
antiferromagnetic metal EuSnP through single-
crystal neutron diffraction experiments. The
magnetic propagation vector in the magnetically ordered phase was determined to be $(0,0,1/2)$, indicating that commensurate
antiferromagnetic ordering is realized in this material. The detailed
magnetic structure analysis revealed a collinear A-type
antiferromagnetic structure with
ferromagnetic alignment of Eu$^{2+}$ moments within the Eu–P layer. The present findings provide a microscopic basis for understanding the intriguing
magnetic behaviors of EuSnP, as exemplified by the multiple metamagnetic transitions in the
antiferromagnetic state and the strong pressure dependence of the
magnetic transition temperature.
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All authors Mizuki Urai, Hiraku Saito, Daisuke Nishio-Hamane, Taro Nakajima, Rina Takagi
Quantum Gases
Ashton S. Bradley, Tyler W. Neely, Xiaoquan Yu et al. (+1 more)
We review
turbulence in ultracold
quantum gases, using the scalar contact-interaction Bose-Einstein condensate as the reference system for quantized circulation, compressibility,
vortices, sound, and cascades. We focus on the quantitative diagnostics that connect helium and classical phenomenology to microscopic wave-function dynamics: incompressible and compressible kinetic-energy spectra, wave-occupation spectra, spectral fluxes,
vortex-resolved correlations, and velocity statistics. These diagnostics distinguish
equilibrium vortex organization, decaying turbulent relaxation, forced cascade dynamics, and weak-wave
turbulence, and show why power laws alone are insufficient evidence for a cascade. We survey experiments on two-dimensional Onsager clustering, three-dimensional
vortex-line
turbulence, box-trap wave cascades, engineered dissipation, and turbulent equations of state. We close by briefly placing the contact-interaction scalar superfluid system in a broader landscape of nonlocal, multicomponent, fermionic, and driven-dissipative
quantum fluids, where
turbulence concepts can be tested for universality.
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All authors Ashton S. Bradley, Tyler W. Neely, Xiaoquan Yu, Brian P. Anderson
Statistical Mechanics
Fermions on a 1D lattice: localized sources and sinks with dephasing
Elka Bhattacharya, Sushant Saryal, Soumya Ghosh et al. (+1 more)
We study a general one-dimensional spinless fermionic system subject to a localized source, sink, and bulk dephasing. Within the Lindblad framework, we compute the time
evolution of the density profile and spatial correlation functions. We find that the presence of bulk dephasing suppresses certain coherent
quantum features, such as the Friedel oscillations, and it alters the transport dynamics to exhibit two distinct dynamical regimes instead of three as observed in the absence of dephasing. This effect can be understood as the destruction of ballistic motion caused by the dephasing noise. Under strong dephasing, the density profile becomes similar to the one expected for a classical diffusive regime. We also investigate the system in the presence of both a localized source and sink, placed at a distance of $\Delta$. Interestingly,
quantum coherence generates secondary density peaks at integer multiples of the source-sink separation $\Delta$, which are systematically washed out as bulk dephasing drives the system toward the classical diffusive limit.
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All authors Elka Bhattacharya, Sushant Saryal, Soumya Ghosh, Kabir Ramola