Materials Science
Asymmetric Energy Landscapes Control Diffusion in Glasses
Ajay Annamareddy, Bu Wang, Paul M. Voyles et al. (+2 more)
While
diffusion in crystalline solids is quantitatively understood through defect-mediated atomic hops, no comparable quantitative framework exists for glasses. In these systems, the origin of large
diffusion activation energies remains puzzling, despite local rearrangements involving low barriers. Using molecular dynamics simulations of metallic glasses, we decompose
diffusion into random-walk and correlation contributions and find that back-and-forth correlated motion, not local rearrangement barriers, dominates the activation energy, resolving how low-barrier rearrangements yield large macroscopic activation energies. These correlations arise from asymmetry between forward and reverse barriers, a generic feature of disordered energy landscapes. We find that the correlation-driven mechanism is active beyond metallic glass
alloys, including SiO2 and a single-component Lennard-Jones glass. The latter demonstrates that the correlation originates from structural disorder rather than chemical complexity. The framework also explains accelerated surface
diffusion, where reduced activation energies arise primarily from weaker correlations rather than changes in local rearrangement barriers. Our results establish a direct, quantitative link between atomic-scale dynamics and macroscopic transport, providing a predictive basis for kinetics in disordered materials.
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All authors Ajay Annamareddy, Bu Wang, Paul M. Voyles, Izabela Szlufarska, Dane Morgan
Materials Science
From Atomistic Models to Machine Learning: Predictive Design of Nanocarbons under Extreme Conditions
Xiaoli Yan, Millicent A. Firestone, Murat Keceli et al. (+2 more)
The formation of technologically valuable nanocarbon structures under extreme conditions, such as those produced during high-explosive detonations, remains poorly understood but holds significant potential for the development of controlled synthesis pathways. While detonation shockwaves provide the HPHT environment required for nanodiamond formation, subsequent cooling and decompression dictate whether the diamond phase is preserved or transformed into other nanocarbon structures. Here, we employ GPU-accelerated ReaxFF simulations to investigate the graphitization and structural remodeling of detonation nanodiamond under nonlinear quench and pressure-release conditions. We further investigate how the initial nanodiamond morphology influences the resulting transformation products.
Evolution of nanostructure, allotrope, carbon hybridization, and ring statistics are tracked. Rapid cooling combined with slow decompression optimizes cubic diamond retention, whereas slow cooling with rapid pressure release promotes surface-to-core graphitization, producing concentric sp2 layers and hollowed inner shells. Octahedral nanodiamonds evolve into carbon nano-onions, initially forming bucky diamonds that progressively transform into full sp2 structures, while hexagonal prisms preferentially form parallel-stacked graphite layers resembling carbon dots. Lonsdaleite emerges as an interfacial phase, suggesting potential reversibility in the shock-induced graphite-to-diamond transformation pathway transformation route. To extend predictive capabilities, we trained MLP regressors on over 10^5 node-hours of simulations. The model reliably predicts the number of graphitized layers from T-P trajectories with R^2 exceeding 0.90. Collectively, morphological control combined with optimized quench-decompression conditions promote the selective synthesis of nanocarbon allotropes.
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All authors Xiaoli Yan, Millicent A. Firestone, Murat Keceli, Santanu Chaudhuri, Eliu Huerta
Disordered Systems and Neural Networks
Anderson transition in disordered Hatano-Nelson systems
Silvio Barandun
We illuminate the fundamental mechanism responsible for the transition between the non-Hermitian skin effect and defect-induced Anderson localization in the bulk via the study of Lyapunov exponents. We obtain a proof that the change of the topological invariant associated with an
eigenvalue coincides with the eigenvector crossover from non-Hermitian skin effect to Anderson localization, establishing a universal criterion for localization behavior.
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Strongly Correlated Electrons
Continuous symmetry analysis and systematic identification of candidate order parameters for interacting fermion models
Cheng-Hao He, Yi-Zhuang You and Xiao Yan Xu
Symmetry plays a central role in modern physics, from classifying
quantum states to characterizing phases of matter through spontaneous
symmetry breaking. In interacting fermionic systems with multiple internal degrees of freedom, however, determining the full continuous
symmetry group and classifying possible order parameters remain challenging. In this work, we present a systematic framework for analyzing continuous
symmetries and identifying candidate order parameters in such systems. By mapping the
Hamiltonian to a Majorana representation, we obtain the generators of continuous
symmetries from the Lie
algebra of operators that commute with the
Hamiltonian. We then identify the structure of this Lie
algebra using the theory of semisimple Lie
algebras. Building on representation theory, we further develop a systematic method for exhaustively enumerating candidate order parameters. By decomposing the exterior-power representations induced by the
symmetry algebra on the Majorana space and incorporating discrete
lattice symmetries, we classify these order parameters according to the
symmetries they break. (Abridged. Please see the PDF manuscript for the complete abstract and specific model applications.)
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Strongly Correlated Electrons
Symmetric Mass Generation in a Bilayer Honeycomb Lattice with $\mathrm{SU}(2)\times\mathrm{SU}(2)\times\mathrm{SU}(2)/\mathbb{Z}_2$ Symmetry
Cheng-Hao He, Yi-Zhuang You and Xiao Yan Xu
A central question beyond the Landau paradigm is the non-perturbative critical theory of the symmetric mass generation (SMG) transition, where strong interactions gap Dirac
fermions in (2+1) dimensions without triggering spontaneous
symmetry breaking or topological order. While previous studies have already provided evidence for direct SMG transitions in (2+1) dimensions, the
fermion scaling dimension – the key observable for distinguishing candidate critical theories – has not been determined in a controlled unbiased way. In this Letter, using large-scale determinant
quantum Monte Carlo (DQMC) simulations of a
bilayer honeycomb
lattice model with $\mathrm{SU}(2)\times\mathrm{SU}(2)\times\mathrm{SU}(2)/\mathbb{Z}_2$
symmetry, we establish a direct continuous transition by observing the simultaneous opening of single-particle and bosonic gaps at a critical coupling $J_c \approx 2.6$ with correlation length exponent $\nu = 1.14(2)$, while an exhaustive search over all 19
symmetry-inequivalent
fermion bilinear order parameters confirms the absence of any
symmetry breaking. We further obtain the first controlled unbiased estimate of the
fermion anomalous dimension, $\eta_\psi = 0.071(1)$, which deviates significantly from the large-$N$ prediction ($\eta_\psi \approx 0.595$) and variational Monte Carlo estimates ($\eta_\psi \approx 0.62$), thereby placing direct quantitative constraints on SMG criticality. By contrasting with a related $\mathrm{Spin}(5)\times\mathrm{U}(1)/\mathbb{Z}_2$ model that develops an intermediate excitonic phase, we show that pure non-Abelian
symmetry plays a decisive role in stabilizing the direct SMG transition.
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Soft Condensed Matter
Synthesis, Solvent-dependent Self-Assembly and Partial Oxidation of Ultrathin Cerium Fluoride Nanoplatelets
Chiara Moretti, Damien Alloyeau, Benjamin Aymoz et al. (+5 more)
Two-dimensional colloidal nanoplatelets (NPLs) with atomically defined thickness exhibit unique physical properties, yet understanding their formation mechanism and assembly remains essential for tuning their collective behavior. We report an optimized synthesis of triangular cerium-based NPLs with narrow size and shape distributions via thermal decomposition of cerium trifluoroacetate. Combining X-ray diffraction, XPS, and high-resolution STEM, we show that the expected CeF3 NPL structure undergoes partial oxidation, yielding an oxyfluoride composition CeOxFy. Beyond their composition, we investigate how these oleic acid-capped NPLs organize in solution and at interfaces. The choice of solvent governs both the solution-phase organization and the resulting superstructures formed upon evaporation at the
liquid–air interface. In solvents that promote face-to-face stacking in solution, evaporation produces films organized into columnar assemblies tens of micrometers long, with the NPL planes oriented perpendicular to the interface. In contrast, solvents in which NPLs remain individually dispersed yield extended hexagonally ordered superlattices with edge-to-edge stacking spanning several micrometers, where the NPLs lie parallel to the interface in an edge-to-edge arrangement. These results highlight that solvent-mediated interactions and pre-existing organization in solution are decisive factors in determining the outcome of evaporative self-assembly of colloidal nanocrystals.
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All authors Chiara Moretti, Damien Alloyeau, Benjamin Aymoz, Laurent Lermusiaux, Rodolphe Valleix, Benoit Mahler, Marianne Impéror-Clerc, Benjamin Abécassis
Materials Science
Long photoexcited carrier lifetime in a stable and earth-abundant zinc polyphosphide
Zhenkun Yuan, Genevieve Amobi, Shaham Quadir et al. (+16 more)
Halide perovskites have revolutionized optoelectronics by demonstrating that long carrier lifetime can be achieved in materials processed in relatively uncontrolled environments, whereas conventional inorganic
semiconductors typically suffer from short carrier lifetime unless very carefully prepared and postprocessed. Here, we report the discovery of exceptionally long photoexcited carrier lifetime in monoclinic ZnP2, effectively bridging the carrier lifetime gap between direct-gap inorganic
semiconductors and halide perovskites. Through computational screening, ZnP2 is identified as a long carrier lifetime
semiconductor characterized by an unconventional polyphosphide bonding, combining covalently bonded phosphorus chains and polar-covalent Zn-P tetrahedra. Experimentally, ZnP2
crystals synthesized from low-purity precursors exhibit bright band-to-band photoluminescence at 1.49 eV and carrier lifetimes of up to 1 $\mu$s. Further analysis reveals that the polyphosphide bonding of ZnP2 suppresses the formation of deep intrinsic defects, making it defect resistant. Combined with its remarkable environmental stability, ZnP2 presents a highly promising material for
solar absorbers and light emitters. Our work illustrates that underexplored inorganic materials spaces with unusual chemical bonding hold great promise for discovering novel optoelectronic materials.
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All authors Zhenkun Yuan, Genevieve Amobi, Shaham Quadir, Smitakshi Goswami, Guillermo L. Esparza, Gideon Kassa, Gayatri Viswanathan, Joseph T. Race, Muhammad R. Hasan, Jack R. Palmer, Sita Dugu, Yagmur Coban, Andriy Zakutayev, Obadiah G. Reid, David P. Fenning, Kirill Kovnir, Sage R. Bauers, Jifeng Liu, Geoffroy Hautier
Soft Condensed Matter
Modeling cavitation and fibrillation in elastomers and adhesives. Part I: Cohesive instability
S. Mohammad Mousavi, Sarvesh Joshi, Franck Vernerey et al. (+1 more)
Cavitation in soft elastomers and adhesives is often viewed as an elastic instability, commonly tied to the study of incompressible solids. It is the first step prior to fibrillation and ultimate failure in adhesives. Building on the work of Lamont et al. (2025), elastomeric materials are treated as a crosslinked van der Waals fluid. The van der Waals contribution, capturing excluded volume and cohesive forces, is non-(poly)convex, readily providing an intrinsic analytical criterion for cavity nucleation. This work introduces a gradient-enhanced continuum framework that examines the emergence of cavity formation from the perspective of a cohesive instability and corresponding phase transition without requiring a pre-existing defect. The corresponding thermodynamically consistent derivation includes the introduction of a relevant material length scale as well as viscous dissipation associated with
polymer chain disentanglement during the cohesive instability. This work does not study the impending damage that the material undergoes during the cohesive instability and transition from a dense to a rare phase. Interestingly, it is shown that for both strain stiffening and strain softening models (in terms of their shear response), an instability reminiscent of what is expected in the case of cavitation is recapitulated. Simulations reproduce key experimental trends, including the aspect ratio-driven transition from a few large to many small cavities depending on the thickness of an adhesive layer. The framework offers a robust, physically grounded basis for the cohesive instability that drives cavity nucleation, enabling future integration with damage, fracture, and dissipation models to capture the complete cavitation, fibrillation, and failure process.
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All authors S. Mohammad Mousavi, Sarvesh Joshi, Franck Vernerey, Nikolaos Bouklas
Mesoscale and Nanoscale Physics · Cross-listed from physics.optics
Direct observation of ultrafast defect-bound and free exciton dynamics in defect-engineered WS$_2$ monolayers
Tae Gwan Park, Xufan Li, Kyungnam Kang et al. (+7 more)
Defects in two-dimensional transition metal dichalcogenides (TMDCs) broadly affect their optical and electronic properties. Directly capturing the ultrafast processes of
exciton trapping and defect-bound
exciton formation is crucial for understanding and advancing defect-mediated optoelectronics and
quantum technologies. However, the weak transient optical absorption of defect-bound
excitons has limited their experimental observation to date. Here, we report the direct observation of the ultrafast dynamics of defect-bound
excitons in monolayer WS$_2$
crystals with a high density of mono-sulfur vacancies (V$_S$) and W-site defect complexes (S$_W$V$_S$) resulting from synthesis by alkali metal halide-assisted chemical vapor deposition. The dynamics of
excitons bound to these defects, along with their coherent interactions with free
excitons, are elucidated using ultrafast optical spectroscopy. Using above band-edge photoexcitation, we find that both free and defect-bound
excitons simultaneously form within 300 fs from hot carrier relaxation. The defect-bound
excitons exhibit shorter lifetimes than free
excitons, leading to a population difference of the corresponding excitonic states and free
exciton trapping within a 1–100 ps window. Band-edge photoexcitation of free and defect-bound
exciton states reveals ultrafast interconversion within ~150 fs (comparable to our temporal resolution), indicating possible coherent coupling between these states. We further demonstrate efficient up-conversion of defect-bound
excitons to free
excitons with
photon energies up to ~300 meV below the free
exciton resonance. These findings provide insights into the ultrafast dynamics of defect-bound
excitons in TMDCs and their coupling with free
excitons, which are relevant to defect-engineered optoelectronic,
quantum photonic, and valleytronic applications.
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All authors Tae Gwan Park, Xufan Li, Kyungnam Kang, Austin Houston, Liam Collins, Gerd Duscher, David B. Geohegan, Christopher M. Rouleau, Kai Xiao, Alexander A. Puretzky
Statistical Mechanics · Cross-listed from quant-ph
From Classical Stochastic to Monitored Quantum Dynamics: Dynamical Phase Coexistence in East Circuit Models
Marcel Cech, Johan du Buisson, Cecilia De Fazio et al. (+2 more)
Kinetically constrained models have been widely studied in the context of glass formers and non-
equilibrium statistical mechanics. Although their simple local rules often result in structureless static properties, their dynamics exhibit intricate emergent phenomena. In this work, we investigate monitored
quantum circuit models that interpolate between classical
stochastic and
unitary quantum dynamics. For any finite measurement strength, the measurement records provide an experimentally accessible probe of the emergence of dynamical phases. By interpreting space-time resolved records as microstates of a fictitious 1+1D
spin system, we employ thermodynamic concepts that allow us to investigate the dynamical coexistence between an active and inactive phase. We combine insights from classical
stochastic dynamics and numerical simulations of monitored
quantum dynamics to investigate different signatures of this dynamical phase coexistence as the measurement strength is varied. Our results shed light on the persistence of dynamical phase coexistence in the
quantum regime, offering insights into future experimental studies of complex many-body dynamics in
quantum simulators.
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All authors Marcel Cech, Johan du Buisson, Cecilia De Fazio, Federico Carollo, Igor Lesanovsky
Strongly Correlated Electrons
Tackling the Sign Problem in the Doped Hubbard Model with Normalizing Flows
Dominic Schuh, Lena Funcke, Janik Kreit et al. (+2 more)
The Hubbard model at finite chemical potential is a cornerstone for understanding doped correlated systems, but simulations are severely limited by the sign problem. In the auxiliary-field formulation, the
spin basis mitigates the sign problem, yet severe ergodicity issues have limited its use. We extend recent advances with normalizing flows at half-filling to finite chemical potential by introducing an annealing scheme enabling ergodic sampling. Compared to state-of-the-art hybrid Monte Carlo in the charge basis, our approach accurately reproduces exact diagonalization results while reducing statistical uncertainties by an order of magnitude, opening a new path for simulations of doped correlated systems.
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All authors Dominic Schuh, Lena Funcke, Janik Kreit, Thomas Luu, Simran Singh
Superconductivity
Fast Real-Axis Eliashberg Calculations: Full-bandwidth solutions beyond the constant density of states approximation
Alejandro Simon, James Shi, Dominik Spath et al. (+10 more)
Experimentally relevant signatures of superconductivity require access to real-frequency quantities, such as the spectral functions, optical response, and transport properties, yet Migdal-Eliashberg calculations are commonly performed on the imaginary axis and then analytically continued, a step that is numerically delicate and can obscure physically relevant spectral features. Here we present a practical route to solving the finite-temperature Migdal-Eliashberg equations directly on the real-frequency axis, while retaining the effects from the full-bandwidth electronic structure. Our formulation accounts for particle-hole asymmetry through an energy-dependent electronic density of states, avoiding the constant density of states approximation often used in real-axis calculations, and includes a static screened Coulomb contribution. We introduce an efficient numerical technique to solve the Migdal-Eliashberg integrals whose computational cost scales linearly with the real-frequency grid, making high-resolution, full-bandwidth real-axis calculations feasible and providing direct access to the interacting Green's function and derived observables without analytic continuation. As an illustration, we apply the method to H$_{3}$S, where a van-Hove singularity near the
Fermi level produces strong particle-hole asymmetry. The full-bandwidth solution yields noticeably different spectra than the constant density of states approximation and brings the superconducting gap and lineshapes into closer agreement with experiment, highlighting when band-structure details are essential. Furthermore, the methods presented here open the door to time-dependent, nonequilibrium simulations within Eliashberg theory.
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All authors Alejandro Simon, James Shi, Dominik Spath, Eva Kogler, Reed Foster, Emma Batson, Pedro N. Ferreira, Mihir Sahoo, Phillip D. Keathley, Warren E. Pickett, Rohit Prasankumar, Karl K. Berggren, Christoph Heil
Mesoscale and Nanoscale Physics
In-plane magnetic response and Maki parameter of alternating-twist multilayers
Igor Vasilevskiy, Miguel Sánchez Sánchez, Khadija Challaouy et al. (+3 more)
We analytically study the orbital response of alternating-twist multilayer
graphene to an in-plane
magnetic field using the
unitary transformation introduced by Khalaf et al. [Phys. Rev. B 100, 085109 (2019)]. This transformation maps an alternating-twist $N$-layer system onto $N/2$ decoupled twisted
bilayer graphene (TBG) systems with distinct effective twist angles, together with a single decoupled layer for odd $N$, thereby generating a hierarchy of effective magic angles. For systems with an odd number of layers, we find that the orbital in-plane
magnetic response is negligibly small. For even systems, we express the in-plane orbital susceptibility in terms of the corresponding TBG responses in the flat-band regime, which are large compared to the
spin susceptibility and even diverge in the clean limit at charge neutrality near the magic angle. For the finite even-layer systems considered in this work, the in-plane
magnetic response strongly depends on the effective magic angle within the hierarchy: the larger the twist angle, the smaller the total response. Moreover, we find a general relation between the outermost interlayer and total susceptibilities of the system when the corresponding effective TBG subsystem is in the flat-band regime. We finally introduce the in-plane Maki parameter as the ratio of the difference in orbital susceptibility between the normal and superconducting states to the paramagnetic Pauli susceptibility. For TBG, we find values up to 2 near the magic angle. Our analysis shows that for certain magic angles, the interpretation of Pauli-limit violation in alternating-twist multilayers requires taking into account the orbital contribution to the in-plane
magnetic response.
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All authors Igor Vasilevskiy, Miguel Sánchez Sánchez, Khadija Challaouy, Dionisios Margetis, Guillermo Gómez-Santos, Tobias Stauber
Superconductivity
Ultrafast dynamics and light-induced superconductivity from first principles
Alejandro Simon, James Shi, Eva Kogler et al. (+9 more)
Experiments on superconducting materials have unveiled unique emergent properties when they are driven far from
equilibrium. However, a quantitative first-principles treatment that describes experimental observations is lacking. In this work, we develop an ab-initio model for the nonequilibrium response of optically irradiated superconducting films within the framework of conventional electron-
phonon-mediated superconductivity, leveraging new numerical techniques to solve the Migdal-Eliashberg equations directly on the real-frequency axis. This enables us to quantitatively reproduce the optical response of superconducting films in pump-probe experiments and validate our approach on measurements of the differential reflectance of Pb and LaH$_{10}$ in response to a pump excitation. Similar calculations performed on the alkali-doped fulleride K$_3$C$_{60}$ reveal that a photo-induced superconducting state is generated after irradiation by an ultrafast mid-infrared pulse of sufficient intensity, as reported in prior experimental work. The enhancement in this framework is attributed to the excitation of quasiparticles to energies resonant with the strongest electron-
phonon coupling in K$_3$C$_{60}$, in close analogy to the mechanism for enhancement of superconductivity under microwave irradiation, explaining the nature of the photo-induced superconducting state and elucidating the subsequent quasiparticle and
phonon dynamics. Our results suggest that photo-induced superconductivity is accessible in more materials than previously recognized. We demonstrate this by performing calculations on calcium-intercalated graphite, CaC$_6$, and predict a similar photo-induced superconducting gap.
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All authors Alejandro Simon, James Shi, Eva Kogler, Reed Foster, Dominik Spath, Emma Batson, Pedro N. Ferreira, Mihir Sahoo, Rohit Prasankumar, Phillip D. Keathley, Karl K. Berggren, Christoph Heil
Mesoscale and Nanoscale Physics · Cross-listed from quant-ph
Theory of Two-Qubit $T_2$ Spectroscopy of Quantum Many-Body Systems
Hossein Hosseinabadi, Pavel E. Dolgirev, Sarang Gopalakrishnan et al. (+3 more)
Multi-
qubit quantum sensors are rapidly emerging as platforms that extend the capabilities of conventional single-
qubit sensing. In this work we show how suitable pulse sequences applied to a two-
qubit sensor enable separate extraction of the response and noise of a probed environment within a $T_2$ spectroscopy framework. By resorting to representative examples, we demonstrate that this approach can resolve the spatio-temporal spreading of correlations in a many-body system. In particular, the resulting correlated dephasing signal captures features such as the dispersion of low-energy excitations, which manifest as light-cone-like profiles in the propagation of correlations. We further show that non-
equilibrium conditions, for instance those induced by external driving, can modify this profile by producing additional fringes outside the light-cone. As a complementary application, we demonstrate that the method clearly distinguishes between different transport regimes in the system, including ballistic spreading, diffusive broadening, and the crossover between them.
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All authors Hossein Hosseinabadi, Pavel E. Dolgirev, Sarang Gopalakrishnan, Amir Yacoby, Eugene Demler, Jamir Marino
Disordered Systems and Neural Networks
Statistical Mechanics of Random Hyperbolic Graphs within the Fermionic Maximum-Entropy Framework
M. Ángeles Serrano
The intricate relations between elements in natural and human-made systems sustain the complex processes that shape our world, forming multiscale networks of interactions. These networks can be represented as graphs composed of nodes connected by links and, regardless of their domain, they share a set of fundamental structural properties. The family of network models in
hyperbolic space constitutes one of the most advanced frameworks accounting for such properties, including sparsity, the small-world property, heterogeneity and hierarchical organization, high clustering, and scale invariance under network renormalization transformations. These
geometric models also exhibit other intriguing phenomena, such as an anomalous, temperature-dependent phase transition between a
geometric and a non-
geometric phase. In simple graph representations, where network links are unweighted, the model can be derived within a statistical-mechanics framework by maximizing the Gibbs
entropy of the graph ensemble subject to constraints imposed by observations, with links effectively behaving as fermionic particles. In this topical review, I revisit these derivations previously scattered across different sources and complement them, in order to properly contextualize and consolidate
hyperbolic random graphs within the broad framework of the maximum-
entropy principle in the statistical mechanics of complex networks. The approach presented here represents the least-biased prediction of the fundamental set of core network properties and establishes a principled framework for analyzing network structure, offering new perspectives and powerful analytical tools for both theoretical and empirical studies.
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Soft Condensed Matter
Origin of Edge Currents in Chiral Active Liquids
Faisal Alsallom and David T. Limmer
Chiral active
liquids generically exhibit unidirectional edge currents in confinement. While this phenomenon has been attributed to model-specific mechanisms and interpreted through phenomenological equations, a universal understanding of it, and its connection to microscopic dynamics remain absent. Starting from the microscopic equations of motion of a simple interacting two-dimensional model, we find that localized edge currents emerge as a consequence of global angular momentum balance. From these underlying equations, we derive an Ohmic-like conductance law for the mean edge current in the dense phase, and we find it to be intensive, depending only on the density, active torque and substrate drag. For simple geometries, we find the distribution of the edge currents has a closed Gaussian form, with a variance that is intensive, depending only on temperature, density and the aspect ratio of the system. These results are validated numerically using extensive molecular dynamics simulations. This origin of the edge current is shown to extend to other models of
chiral systems where angular momentum is injected in distinct ways.
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Strongly Correlated Electrons
Polaron-driven switching of octupolar order in doped 5d$^2$ double perovskite
Dario Fiore Mosca, Lorenzo Celiberti, Leonid V. Pourovskii et al. (+1 more)
We investigate how doping-induced small polarons impact the low-temperature multipolar orders of the $5d^2$ double perovskite Ba$_2$CaOsO$_6$. By computing intersite exchange interactions between 5d$^1$ localized hole polarons and 5d$^2$
magnetic ions from first principles, we demonstrate the reversal of the dominant octupolar exchange from
ferromagnetic to
antiferromagnetic. Solving the corresponding effective
Hamiltonian we find this reversal to account for the progressive suppression of the ferro-octupolar order and the reduction of the ordering temperature upon Na doping. These findings clarify previously ambiguous experimental observations and demonstrate that charge doping in the form of small polarons offers a viable route to tuning intersite exchange interactions in
spin-orbit-entangled materials, enabling the emergence of novel
quantum orders.
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All authors Dario Fiore Mosca, Lorenzo Celiberti, Leonid V. Pourovskii, Cesare Franchini
Strongly Correlated Electrons
Removing nodal and support-mismatch pathologies in Variational Monte Carlo via blurred sampling
Zhou-Quan Wan, Roeland Wiersema and Shiwei Zhang
Variational Monte Carlo (VMC) is a powerful and fast-growing method for optimizing and evolving parameterized many-body wave functions, especially with modern neural-network
quantum states. In practice, however, the
stochastic estimators that form the backbone of the method can become unstable or biased due to the presence of nodes, a ubiquitous feature of
quantum wave functions. In the continuum, this results in heavy-tailed
estimators with potentially divergent variances, while in discrete
Hilbert spaces the sampling distribution can miss parts of the support needed to form unbiased
estimators. These statistical pathologies lead to unreliable optimization trajectories in
stochastic reconfiguration or incorrect variational dynamics in time-dependent Variational Monte Carlo (t-VMC), and severely limit the power of the numerical simulations. We introduce blurred sampling to address these difficulties. The method has a number of rigorous properties that make it well-behaved, effective and computationally efficient. Additionally, it is a post-processing approach that can be used without modifying the underlying sampler and incurs only minimal overhead. We demonstrate its effectiveness in a broad range of problems – including ground state optimization in both continuum and discrete settings, as well as in time-dependent variational Monte Carlo, where it resolves previously identified failure modes – and further apply it to large-scale problems in
spin dynamics. This work establishes a broadly applicable framework for robust VMC and t-VMC calculations.
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Statistical Mechanics · Cross-listed from hep-th
Moments in the CFT Landscape
Li-Yuan Chiang, David Poland and Gordon Rogelberg
We develop a novel numerical bootstrap for
unitary, crossing-symmetric conformal field theories, focusing on moment observables defined as weighted averages over conformal data. Providing a global and coarse-grained probe of the operator spectrum, this framework yields numerically rigorous bounds on the operator distribution using standard semidefinite programming techniques. In the heavy correlator regime, these bounds remain robust and converge rapidly towards analytically-derived power laws. At finite external dimensions, low-lying moments capture corrections to analytic heavy limit results, while reproducing familiar bootstrap solutions such as Ising-model kinks on the boundary of moment space. Most importantly, the moment bootstrap reveals new features in previously unexplored regions of the bootstrap landscape. The lower bounds on moment variables exhibit two continuous families of kinks persisting across $2 < d < 6$, reflecting nontrivial spectral reorganizations connected to underlying operator decoupling phenomena. These results demonstrate that moment variables uncover bootstrap solutions and collective structures that are difficult to access within traditional numerical approaches.
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Strongly Correlated Electrons
Understanding Anomalous Magnetothermal Transport via Disentangling Shear and Compression Phonons
Haoting Xu, Antoine Matar and Hae-Young Kee
Magnetothermal transport in various frustrated magnets exhibits striking field-dependent anomalies that deviate from conventional
magnon or
phonon transport. To understand such anomalies, we derive an effective
spin-
phonon Hamiltonian in which
phonons with different polarizations couple selectively to distinct
spin operators in the strong
spin-orbit coupling limit, and show that
symmetry-constrained
spin-
lattice coupling naturally leads to mode-selective
spin-
phonon interactions. As a result, compression and shear
phonon modes contribute to
spin heat current across different
magnetic-field regimes. Using a Landauer transport framework combined with exact diagonalization of
spin chains coupled to a
phonon bath, we show that this mechanism produces a characteristic peak-dip-peak structure in the field dependence of heat current, providing a microscopic explanation for field-induced transport anomalies in
spin-orbit-coupled Mott
insulators.
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Superconductivity
Light induced magnetization in d-wave superconductors
Maxim Dzero and Vladyslav Kozii
We develop a microscopic theory of the inverse Faraday effect in $s$- and $d$-wave
superconductors. An extended version of the Keldysh–Nambu quasiclassical formalism, which retains the particle-hole asymmetric terms responsible for the branch population imbalance, is used to compute the dc component of the nonlinear current density induced by an external monochromatic radiation. We demonstrate how the branch population imbalance produces a nonvanishing nonlinear and nonlocal dc response, evaluate the magnitude of the induced current, and obtain estimates for the induced static magnetization. For $d$-wave pairing we identify a qualitatively new contribution: the radiation induces a linear-in-field oscillation of the order-parameter amplitude – the Schmid-
Higgs mode – in the $B_{1g}$ channel, which feeds the rectified response with a weight proportional to the pair susceptibility and is therefore resonantly enhanced at the pair-breaking threshold. This contribution is
symmetry-forbidden for an isotropic $s$-wave gap, so the light-induced magnetization serves both as a dc-channel probe of the
Higgs mode and as a discriminator of the pairing
symmetry. Experimental implications of our theory and future extensions of our work are briefly discussed.
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Strongly Correlated Electrons
Spin-Charge Groups for Fermions in Fluids and Crystals: General Structures and Physical Consequences
Arist Zhenyuan Yang and Zheng-Xin Liu
Known
symmetry groups are insufficient to describe the various couplings among
spin, charge, and spatial degrees of freedom in fermionic systems. To address this problem, we introduce
spin-charge groups (SCGs), which provide a unified framework for fermionic
symmetries. SCGs incorporate
spin and charge operations as `internal'
symmetries, spatial and temporal operations as `external'
symmetries, together with their couplings and projective twists. After deriving the general group structure of SCGs, we explore their applications in concrete physical systems, including $^3$He superfluids, charge-4e
superconductors, collinear magnets with
spin-fluxes, and
superconductors with coexisting
magnetic orders. We show that SCGs can enforce additional band degeneracies, Chern numbers and cross
spin-charge responses. Hence SCGs provide a
symmetry-based route toward the classification and exploration of new phases of matter even when strong interactions are included.
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Materials Science
Polarization Dynamics in Ferroelectrics: Insights Enabled by Machine Learning Molecular Dynamics
Dongyu Bai, Ri He, Junxian Liu et al. (+1 more)
Ferroelectric materials with switchable spontaneous polarization underpin non-volatile
memories, transistors, sensors, and emerging neuromorphic chips. Their performance and stability are governed by polarization dynamics and domain kinetics, making a microscopic understanding of these processes and precise atomic level control of polarization domains key challenges for next-generation ferroelectric electronics. Due to the limitations of the characterization technology with atomic level in experiment, high precision atomic simulations become important. First principles calculations are inherently limited in accessible length and time scales, making it difficult to capture the complex features of dynamic processes. Machine learning molecular dynamics (MLMD) offers a compelling solution by encoding
quantum-mechanical accuracy into force fields, thereby enabling large scale dynamic simulations with near first-principles fidelity. This Perspective highlights the advantages of MLMD for simulating polarization switching, domain nucleation and migration, topological polar textures and
curvature-driven ferroelectric phenomena, while providing a systematic overview of recent progress in these areas. We further discuss methodological challenges that limit predictive capability, including long range electrostatics, coupled
lattice-
spin degrees of freedom in multiferroics, and data efficient pre-training of large atomistic models. Corresponding advances in long range aware force fields,
spin dependent machine learning models, and large scale pretraining are expected to move MLMD toward a genuinely predictive framework for the design of ferroelectric and multiferroic materials.
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All authors Dongyu Bai, Ri He, Junxian Liu, Liangzhi Kou
Mesoscale and Nanoscale Physics
Comment on: "Coherent perfect absorption: Zero reflection without linewidth suppression"
Rui-Chang Shen and Jie Li
A recent paper, Phys. Rev. Research 8, 013261 (2026), claims that the polaromechanical normal-mode splitting (NMS) measured in Nat. Commun. 16, 5652 (2025) is not true based on their two results: $i$) there is no true splitting in the linear-scale spectrum; $ii$) the total or intrinsic decay rate of the cavity-
magnon polariton, set by the imaginary part of the pole of the total output spectrum, remains unchanged under the coherent-perfect-absorption (CPA) condition. In this comment, we indicate that $i$) there is NMS in both the linear and logarithmic scales of our spectra in a narrow frequency range around the CPA frequency; $ii$) the total decay rate defined via the pole of the spectrum cannot characterize the vanishing effective decay rate at the CPA frequency (known as the monochromaticity of the CPA), and thus this parameter is irrelevant to the NMS measured in our experiment in a narrow frequency range around the CPA frequency. Consequently, their results above are either false or irrelevant, and thus cannot support their claim on the polaromechanical strong coupling measured in our experiment.
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Quantum Gases
Systematic solitary waves by linear limit continuation from two anisotropic traps in two-dimensional Bose-Einstein condensates
Wenlong Wang
Linear limit continuation was recently developed as a systematic and effective method for constructing numerically exact solitary waves from their respective linear limits. In this work, we apply the technique to two typical anisotropic harmonic traps in two-dimensional Bose-Einstein condensates to further establish the method and also to find more solitary waves. Many wave patterns are identified in the near-linear regime and they are subsequently continued into the Thomas-
Fermi regime, and then they are further continued into the isotropic trap if possible. Finally, the parametric connectivity of the pertinent solitary waves is also discussed.
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Soft Condensed Matter
The Group of Closed Symmetric Flat Foldable Non-Euclidean Curved Crease Origami is not Rigid Foldable: A Simple Geometric Proof
Clark C. Addis, David M. Boston, Hunter Pruett et al. (+2 more)
We present a novel
parabolic reflector system capable of generating a broader class of shapes beyond canonical parabolas. Using a discretized framework, we construct meshes corresponding to key families of developable surfaces, including generalized cylinders, tangent developables, and generalized cones. Both Euclidean and non-Euclidean crease patterns are examined, and we demonstrate that no isometric transformation exists between distinct configurations within this system. This result highlights a fundamental limitation of purely developable models and motivates the incorporation of controlled stretching. We propose that enabling stretch accommodation would allow transitions between configurations, laying the groundwork for a generalized theory of curved-crease stretching. Such a framework has potential applications in understanding complex biological folding systems, including the deployment mechanics of the earwig wing.
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All authors Clark C. Addis, David M. Boston, Hunter Pruett, Phillip Buskohl, Andres F. Arrieta
Strongly Correlated Electrons
Angle-Resolved Berry Curvature via Nonlinear Hall Effect of Ballistic Electrons
Louis Primeau, Qiong Ma and Yang Zhang
Berry
curvature fundamentally dictates the topological ground state, anomalous transport and optical properties of
quantum materials. However, directly mapping its momentum-space distribution in real materials remains an outstanding experimental challenge. Here, we present an inverse method for reconstructing the abelian Berry
curvature of a single band using angle-resolved measurements of the transverse conductance. Our inversion relies on a
symmetry-constrained statistical model with two hyperparameters that can be inferred directly from the nonlinear
Hall conductance, yielding a parameter-free inversion method. We demonstrate the feasibility of our method using simulated measurements of tight-binding models of WSe$_2$ and $ABC$-stacked trilayer
graphene.
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Statistical Mechanics · Cross-listed from quant-ph
CaRBM: A Fixed-Depth Quantum Algorithm with Partial Correction for Thermal State Preparation
Omar Alsheikh, A. F. Kemper, Ermal Rrapaj et al. (+2 more)
We introduce the CaRBM
algorithm for fixed-depth thermal state preparation. Our
algorithm is based on thermal state purification and uses the Restricted Boltzmann Machine (RBM) block-encoding scheme to implement the imaginary-time propagator $e^{-\beta H}$, which is implemented in the
quantum circuit in a fixed-depth manner via Cartan decomposition. Our
algorithm performs best at high temperatures, with the success probability of the block encoding decreasing as the temperature decreases. To increase the success probability, we have devised a correction scheme for the block-encoding that increases the temperature range our
algorithm reliably probes. We demonstrate our
algorithm by calculating the partition function zeros of the XXZ model and the phase diagram of the Gross-Neveu model, which is a model of strongly interacting relativistic
fermions.
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All authors Omar Alsheikh, A. F. Kemper, Ermal Rrapaj, Evan J. Rule, Goksu C. Toga
Soft Condensed Matter
Physical Approaches to Metabolic Scaling in Living Systems
Efe Ilker, Michael Hinczewski, Xingbo Yang et al. (+1 more)
Living systems continuously transform matter and energy through the chemical processes that constitute their metabolism. The overall metabolic rate of an organism correlates positively with its body mass, however both the exact scaling behavior and possible explanations for this behavior have been under intense debate for two centuries. This review synthesizes empirical findings and theoretical frameworks on the energetics of living systems from an interdisciplinary perspective, with a focus on physical concepts. A general thermodynamic framework to study metabolism is laid out, together with a coarse-grained description of metabolic biochemistry. The rich history of experimental work in this field is surveyed, revealing a variety of metabolic scaling patterns at different levels of biological organization, from individual
cells to whole populations. Several biophysical models proposed to explain the sublinear scaling of metabolic rate with body mass are summarized. Though the traditional focus has been on adult organisms, the review also highlights recent advances that probe metabolism during development. Improvements in experimental techniques, extensive
datasets, and a host of open questions, suggest the field will continue gaining momentum in the near term. The review concludes with an outlook for this future progress: an interdisciplinary approach to elucidate metabolic scaling across different developmental stages and organism sizes.
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All authors Efe Ilker, Michael Hinczewski, Xingbo Yang, Frank Jülicher