Statistical Mechanics · Cross-listed from physics.data-an
Beyond the Central Limit: Universality of the Gamma Distribution from Padé-Enhanced Large Deviations
Mario Castro and José A. Cuesta
The central limit
theorem provides the theoretical foundation for the universality of the normal distribution: under broad conditions, the asymptotic distribution of a sum of independent random variables approaches a Gaussian. Yet, physical systems described by positive random variable – from earthquakes to microbial growth to epidemic spreading – consistently exhibit gamma rather than Gaussian statistics – what leads to field-specific mechanistic explanations that are non robust to small changes in the model details. We show that gamma distributions emerge naturally from large deviation theory when Padé approximants replace
polynomial expansions of the derivative of the scaled cumulant generating function, respecting positivity constraints that the central limit
theorem violates. Gamma universality thus emerges as the constrained analog of Gaussian universality, providing a mechanism-free explanation for its pervasive appearance across different disciplines.
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Materials Science
Active learning-enabled multi-objective design of thermally conductive and mechanically compliant polymers
Yuhan Liu, Jiaxin Xu, Renzheng Zhang et al. (+2 more)
Polymers are attractive in applications like flexible electronics and thermal interface materials due to their mechanical compliance and processability. However, conventional
polymers have low thermal conductivity (TC), limiting their heat dissipation performance. Identifying
polymers that simultaneously achieve high intrinsic TC and mechanical flexibility (i.e., low modulus) remains a challenge. Here, we develop an active learning (AL) framework based on multi-objective
Bayesian optimization (MOBO) to discover
polymers exhibiting both high TC and low bulk modulus. Initially, a high-throughput molecular dynamics (MD) pipeline generated an initial
dataset, and independent Deep Kernel Learning (DKL) surrogate models were trained for TC and bulk modulus to predict properties and uncertainties. Using the parallel noisy expected hypervolume improvement (qNEHVI) acquisition function, the framework iteratively screens a larger unlabeled
polymer database, systematically recommends new
polymer candidates for MD evaluation, and updates the DKL models with newly acquired data. Ultimately, six candidates were identified on the Pareto front, representing optimal trade-offs between TC and modulus. Interpretability analysis further revealed molecular features associated with these trade-offs, and synthesizability assessment supported the practical relevance of the selected candidates. By combining MD simulations with AL-enabled MOBO, our workflow mitigates data scarcity, reduces development time, and provides actionable guidance for designing multifunctional
polymers tailored for different applications.
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All authors Yuhan Liu, Jiaxin Xu, Renzheng Zhang, Meng Jiang, Tengfei Luo
Other Condensed Matter
Tunable Floquet selection rules in a driven Ising chain
Rishi Paresh Joshi, Sanchayan Banerjee, Sneha Narasimha Moorthy et al. (+1 more)
We study a periodically driven
spin-$1/2$ Ising chain with a nearest-neighbour coupling and longitudinal field while a weak transverse field induces single-
spin flips. Through Floquet perturbation theory (FPT), we obtain signatures of
Hilbert space fragmentation (HSF) and an unconventional form of dynamical localisation which we call the Floquet freezing. Our analysis suggests that these observations emerge due to a single Floquet selection rule that dictates the prethermal dynamics. For a special value of the field-to-interaction strength ratio together with commensurate drive periods, this rule permits only a constrained subset of bulk
spin flips, leading to prethermal HSF in the full
spin-$1/2$
Hilbert space. Under open boundary conditions, the same rule suppresses boundary
spin flips up to higher order in perturbation and produces long-lived prethermal edge
memory, which is neither topological in origin nor is a strong zero mode. Furthermore, under periodic boundary conditions, the largest surviving fragment is exactly the PXP sector at leading order and therefore exhibits Floquet-inherited scar phenomenology in the prethermal window. At higher commensurate ratios of field strength to interaction strength, all first-order single-
spin-flip channels are suppressed and the system enters a regime of Floquet freezing. Hence, our study leverages the selection rules obtained through Floquet perturbation theory to obtain exotic prethermal phenomena at different parameter regimes.
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All authors Rishi Paresh Joshi, Sanchayan Banerjee, Sneha Narasimha Moorthy, Tapan Mishra
Materials Science
Quantum Saturation of the Electro-Optic Effect
Aiden Ross, Sankalpa Hazra, Albert Suceava et al. (+4 more)
Future
quantum computing architectures require electro-optic materials that maintain a strong, stable performance at cryogenic temperatures. In conventional electro-optic materials, large electro-optic coefficients are often confined to narrow temperature windows near structural phase transitions, where small changes in temperature lead to large changes in the electro-optic response. Using thermodynamic analysis, phase-field simulations, experimental growth and cryogenic optical measurements we show that
quantum fluctuations can be harnessed to overcome this trade-off. By tuning the ferroelectric phase boundaries down to 0 K,
quantum fluctuations induce a saturation regime in which a large electro-optic response becomes nearly temperature-independent below 25 K. We demonstrate that the phase boundaries can be tuned through either strain in BaTiO3 or through chemical composition in Ba1-xCaxTiO3, leading to a large, temperature insensitive, cryogenic electro-optic effect comparable to bulk BaTiO3 at room temperature; the performance exceeds BaTiO3-on-Si by over an order of magnitude. These findings establish a general design principle for engineering high-performance electro-optic materials for cryogenic applications.
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All authors Aiden Ross, Sankalpa Hazra, Albert Suceava, Dylan Sotir, Darrell G. Schlom, Venkatraman Gopalan, Long-Qing Chen
Quantum Gases
Intercavity phonons and dynamics in coupled polariton cavities
Iliana Carmona-Moreno, Grover Andrade-Sánchez, Hugo A Lara-García et al. (+2 more)
Intercavity polaritons, hybrid quasiparticles with spatially separated photonic and excitonic components, provide a platform to engineer structured light-matter states. We show that resonant driving of the middle polariton branch leads to a qualitatively distinct dynamical regime in which coherent Rabi oscillations are suppressed, and the system evolves monotonically toward its steady state. Including interactions, we demonstrate that this regime supports Bogoliubov excitations with a
phonon-like dispersion at low momenta. These collective modes inherit interactions from the excitonic fraction, while preserving the intrinsically intercavity nature of the quasiparticles.
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All authors Iliana Carmona-Moreno, Grover Andrade-Sánchez, Hugo A Lara-García, Giuseppe Pirruccio, Arturo Camacho-Guardian
Soft Condensed Matter
Thickness effects in the electromechanical stability of charged biological membranes
Sirui Ning, Yannick A. D. Omar, Karthik Shekhar et al. (+1 more)
Understanding how electric fields destabilize biological membranes is important for electroporation-based technologies and bioelectronic interfaces. However, theoretical descriptions of this phenomenon remain fragmented. Existing theories treat either electrostatics in membranes of finite thickness or electrohydrodynamic flows at idealized zero-thickness interfaces, leaving unresolved a unified description that simultaneously incorporates finite membrane thickness, surface charge, and bulk electrohydrodynamics. Here, we apply a recently-developed, dimension-reduction framework that captures the coupled electrohydrodynamic and mechanical effects governing height fluctuations of a charged lipid
bilayer of thickness $\delta$ in an electrolyte characterized by Debye screening length $\lambda$. We derive voltage- and charge-dependent renormalizations of the effective surface tension and bending
rigidity, along with a dispersion relation governing undulatory instabilities. A wide range of prior theoretical results arise as limiting cases of our more general theory when finite-thickness effects are neglected or screening is asymptotically strong. The key new contribution arises from traction moments generated across the finite membrane thickness, which are absent in zero-thickness descriptions. Under physiological screening ($\delta/\lambda\sim 4$), these contributions account for more than $>70\%$ of the total electrostatic correction to both surface tension and bending
rigidity. The theory further reveals that surface charges can stabilize the membrane at physiological ionic strengths, increasing the effective tension and shifting electroporation thresholds in a manner that depends on charge asymmetry between the leaflets.
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All authors Sirui Ning, Yannick A. D. Omar, Karthik Shekhar, Kranthi K. Mandadapu
Statistical Mechanics · Cross-listed from quant-ph
Initial State Memory in Finite Random Brickwork Circuits
Jakob Bannister, Katja Klobas, Colin Rylands et al. (+1 more)
We ask under what conditions a finite brickwork
circuit of random gates retains local information about the initial state. To answer this question we measure the averaged Frobenius distance between the reduced states obtained by evolving two arbitrary initial states and tracing out a portion of the system. By characterising this distance exactly at all times we find that the information is retained if the environment – the subsystem traced out – is smaller than half of the system and washed away otherwise. We also find that, while the dynamics of the Frobenius distance depends on the specific initial states chosen, this dependence becomes increasingly weak for large scales and eventually the Frobenius distance attains a universal form as a function of time. Finally, we show that by introducing weak enough boundary dissipation, one can observe a phase transition between a
memory preserving phase and one where the information is completely lost.
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All authors Jakob Bannister, Katja Klobas, Colin Rylands, Bruno Bertini
Materials Science
Structural Chart of Copper-Silver Nanoalloys through machine learning
Manoj Settem, Emanuele Telari, Antonio Tinti et al. (+2 more)
Nanoalloys (or
alloy nanoparticles) are an important class of materials that are promising for their functional properties. However, designing synthesis protocols to control their structure and chemical ordering is rather challenging. Part of this difficulty stems from the lack of information on their metastable and stable structures. Here, we develop a general computational framework to construct a structural chart of nanoalloys using 38-atom AgCu nanoalloys as a model system. Initially, the
equilibrium structural distribution is sampled using parallel tempering combined with molecular dynamics (PTMD). Using a machine learning (ML) based approach, the vast number of sampled configurations are classified into various structural classes. This ML approach produces a single three-dimensional map in which all structures and compositions can be visualized and discriminated. Finally, a finite-temperature structural chart is constructed which provides information on the dominant structures across the entire range of compositions and temperatures. In addition, the structural chart reveals significant differences in thermal stability between nanoalloys and bulk
alloys. The presented framework provides an effective route to compute and map the vast structural and chemical space of multicomponent nanoparticles, paving the way to the rational design of functional nanoalloys.
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All authors Manoj Settem, Emanuele Telari, Antonio Tinti, Riccardo Ferrando, Alberto Giacomello
Materials Science
Ferromagnetic Spin Glass State and Anomalous Hall Effect in Topological Semimetal Candidate Mn2Sb2Te5
M.M. Sharma, Ankush Saxena, S.M. Huang et al. (+3 more)
Materials that intrinsically possess both magnetism and topological states represent a key frontier of
quantum materials research. Recently, Mn2(Bi/Sb)2Te5 has emerged as a promising candidate for hosting topological surface states coupled with intrinsic
magnetic order, making it a potential
magnetic Weyl semimetal. In this study, we investigate the
magnetic and transport properties of Mn2Sb2Te5 single
crystals. The magnetization measurements reveal a
spin glass state with field-induced ferromagnetism. Although heat capacity measurement indicates the absence of long-range order, the intrinsic magnetization in Mn2Sb2Te5 significantly affects its electrical properties, as demonstrated by the anomalous
Hall effect. This work provides valuable insights into the magnetism and the electronic properties of Mn2Sb2Te5, establishing Mn2(Bi/Sb)2Te5 system as a compelling platform for exploring the interplay between magnetism and non-trivial band
topology, enabling emergent
quantum phases and novel transport responses not accessible in non-
magnetic systems.
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All authors M.M. Sharma, Ankush Saxena, S.M. Huang, Santosh Karki Chhetri, Jin Hu, V.P.S. Awana
Materials Science
Ultrafast Sintering
Jian Luo
This Perspective critically assesses recent advances in ultrafast sintering and highlights open scientific questions and emerging technological opportunities. Mechanistic studies of flash sintering indicate that the flash event initiates as a coupled thermal and electrical runaway, while rapid densification is enabled by ultrahigh heating rates and elevated sintering temperatures. Building on this understanding, ultrafast sintering has been realized without passing electric currents through the specimens via multiple approaches, including rapid thermal annealing (using intense infrared heating), ultrafast high-temperature sintering (in which specimens are sandwiched between graphite felt heaters), blacklight sintering (employing blue
laser or intense ultraviolet irradiation), atmospheric-pressure
plasma sintering, and induction ultrafast sintering (utilizing skin currents in direct induction heating or no current in the specimens in susceptor-heating mode). Reactive ultrafast synthesis and sintering have also been demonstrated. Although several hypotheses have been proposed, the mechanisms governing ultrafast sintering and its kinetics warrant further investigation. In particular, reactive ultrafast synthesis and sintering of compositionally complex ceramics are scientifically intriguing to understand while also presenting technological opportunities. The expanding range of ultrafast sintering methods provides a versatile platform for high-throughput materials discovery, especially in the rapidly growing field of high-
entropy and compositionally complex ceramics, which feature vast compositional spaces to explore.
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Quantum Gases · Cross-listed from quant-ph
Quantum simulation of Motzkin spin chain with Rydberg atoms
Kaustav Mukherjee, Hatem Barghathi, Adrian Del Maestro et al. (+1 more)
Motzkin
spin chain is a well-known mathematical model with connections to
symmetry-protected topological phases, such as the Haldane phase, as well as to concepts in the AdS/CFT correspondence. They exhibit highly entangled ground states that violate the area law and are exceptionally difficult to simulate with conventional numerical methods. Numerical simulations of the Motzkin ground state become further challenging at large system sizes due to their high-dimensional
spin structure, rendering it a natural test bed for
quantum simulation with ultra-cold systems. Here, we propose a Rydberg-atom based
quantum simulation scheme that effectively realizes Motzkin
spins using an experimentally accessible set of parameters. We show that the resulting effective Motzkin ground state reproduces the characteristic
entanglement scaling and the block-structure properties of the reduced density
matrix associated with the ideal Motzkin state. Our results establish a pathway toward a concrete experimental realization of Motzkin
spins beyond purely mathematical constructions, opening avenues for exploring other similar exotic non-area-law entangled phases in programmable Rydberg simulators.
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All authors Kaustav Mukherjee, Hatem Barghathi, Adrian Del Maestro, Rick Mukherjee
Strongly Correlated Electrons
Topological Filtering and Emergent Kondo Scale
Ryosuke Yoshii and Rio Oto
We study the Kondo effect induced by a topological
soliton in a one-dimensional Dirac system with the sign-changing mass term. The
soliton hosts a localized zero mode whose spatially extended wavefunction leads to a momentum-dependent exchange coupling with itinerant electrons. We show that this structure generates a nontrivial form factor that suppresses high-energy scattering processes, resulting in an energy-dependent effective Kondo coupling. As a consequence, the real-space structure of the
soliton directly controls the emergent Kondo scale. This work establishes a mechanism by which topological defects control many-body energy scales through their wavefunction structure, suggesting a general principle for engineering many-body energy scales via
topology.
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Superconductivity
Magnetic flux distribution, quasiparticle spectroscopy, and quality factors in Nb films for superconducting qubits
Amlan Datta, Bicky S. Moirangthem, Kamal R. Joshi et al. (+6 more)
Niobium is a practical material platform for superconducting microwave
circuits; however, device-level performance can vary significantly depending on film growth and processing conditions. We compare three epitaxial Nb films grown on $c-$plane sapphire substrates under nominally identical conditions, except for the deposition temperature. To correlate internal quality factors, $Q_{\mathrm {i}}$, with material properties, we combine magneto-optical imaging of
magnetic flux distribution with quasiparticle spectroscopy via measurements of the London penetration depth, $\lambda(T)$. In the low-$Q_{\mathrm i}$ film, there is a lesser ability to screen the
magnetic field and an irregular temperature variation of $\lambda(T)$, implying the existence of localized in-gap states. High $Q_{\mathrm i}$ films show the opposite trend. We conclude that our measurements provide an efficient method for characterizing and optimizing superconducting films for
quantum informatics applications.
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All authors Amlan Datta, Bicky S. Moirangthem, Kamal R. Joshi, Anthony P. Mcfadden, Florent Lecocq, Raymond W. Simmonds, Makariy A. Tanatar, Matthew J. Kramer, Ruslan Prozorov
Superconductivity
A Zero-Bias Superconducting Voltage Amplifier Based on the Bipolar Thermoelectric Effect
Giacomo Trupiano, Giorgio De Simoni and Francesco Giazotto
We introduce a zero-bias superconducting voltage amplifier that harvests energy from a thermal gradient by exploiting negative differential resistance (NDR) in an asymmetric tunnel junction. The device is based on an asymmetric
superconductor-
insulator-
superconductor (SIS) junction with an energy-gap ratio of $\Delta_1/\Delta_2 = 0.5$, connected in series with a load resistor. Owing to the superconducting bipolar thermoelectric effect, the current-voltage characteristic of the junction exhibits a region of NDR, in which the net current flows opposite to the applied voltage. This mechanism enables voltage amplification in the absence of any external electrical bias, relying solely on the temperature difference between the electrodes ($T_H \simeq 1$ K, $T_B \simeq 20$ mK). Numerical simulations predict a voltage gain of 20 dB, a 1 dB compression point at an input amplitude of 2 $\mu$V, and a total harmonic distortion below $-50$ dB. The input-referred noise is approximately 1 nV/$\sqrt{Hz}$, with an associated thermal load on the order of nanowatts. The frequency response is broadband from near DC, with a $-3$ dB cutoff around 180 MHz, set by the RC time constant of the junction. Using Al-, Al-Cu-, and AlO$_x$-based technologies, the amplifier is compatible with conventional superconducting
circuit fabrication processes. These findings demonstrate that thermoelectric superconducting junctions can deliver bias-free voltage amplification from near DC up to about 200 MHz, making them promising candidates for transition-edge sensor readout,
quantum circuit instrumentation, and low-frequency cryogenic signal processing.
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Mesoscale and Nanoscale Physics
Strain-Engineered Deterministic Quantum Dots for Telecom O-Band Emission Using Buried Stressors
Imad Limame, Ching-Wen Shih, Kartik Gaur et al. (+7 more)
The deterministic realization of
quantum light sources operating at telecom wavelengths is essential for long-distance fiber-based
quantum communication and distributed
quantum computing. In this work, we demonstrate that telecom O-band emission can be achieved from site-controlled InGaAs/GaAs
quantum dots (QDs). Our concept utilizes a buried AlAs/Al$_2$O$_3$ stressor layer with the unique feature that induces a well-defined and controllable tensile strain field at the growth surface, enabling both a
redshift of QD emission to the $\sim$1.3~\mu m range and site-selective nucleation at the mesa centers. This concept eliminates not only the need for strain-reducing layers (SRLs), which are known to degrade optical coherence, but also provides spatial control and spectral tunability. The grown telecom QDs show pure single-
photon emission with $g^{(2)}(\tau) = (5.0 \pm 1.0) \times 10^{-2}$ at 4 K and $(2.8 \pm 0.3) \times 10^{-1}$ at 77~K, demonstrating the
quantum nature and thermal stability of the emitters. The emission characteristics of complex excitonic states are analyzed using 8-band $k \cdot p$ and configuration-interaction modeling, which quantitatively reproduces the experimental observations. Finally, we present a theory-supported strategy to further
redshift the emission toward the center of the O-band and beyond by employing a multi-buried-stressor approach. This combined framework of experiment and theory establishes the buried stressor concept as a scalable route toward highly coherent, position-controlled O-band
quantum emitters compatible with industrial photonic integration.
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All authors Imad Limame, Ching-Wen Shih, Kartik Gaur, Martin Podhorský, Sarthak Tripathi, Setthanat Wijitpatima, Aris Koulas-Simos, Chirag C. Palekar, Petr Klenovský, Stephan Reitzenstein
Strongly Correlated Electrons · Cross-listed from quant-ph
Two-parameter Family-Vicsek scaling in a dissipative XXZ spin chain
Cătălin Paşcu Moca, Doru Sticlet, Tamás Vicsek et al. (+1 more)
Family-Vicsek (FV) scaling provides an understanding for the growth and finite-size saturation of fluctuations in classical systems. Here, we extend the FV roughness to transferred segment magnetization after
quantum quenches in a dissipative XXZ
spin chain with homogeneous gain and loss, starting from a nonequilibrium steady state with finite magnetization. In the non-interacting limit, we derive a closed-form expression for the roughness in the presence of dissipation. It displays two-parameter FV scaling and smoothly interpolates between the clean ballistic behavior and the dissipation dominated scalings. For interacting chains, tensor-network simulations show that the non-dissipative ballistic growth at finite magnetization is robust, whereas the full Lindblad
evolution is generically controlled by the dissipative relaxation time and exhibits a dissipation-dominated collapse.
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All authors Cătălin Paşcu Moca, Doru Sticlet, Tamás Vicsek, Balázs Dóra
Superconductivity
Glassy magnetic freezing of interacting clusters in LK-99-family materials
Serafim Teknowijoyo, Domenico Napoletani, Vahan Nikoghosyan et al. (+1 more)
We report reproducible magnetization anomalies appearing below room temperature in copper-doped apatite materials belonging to the LK-99 family synthesized via hydrothermal methods. These anomalies are observed consistently across samples prepared under comparable conditions. Although the extracted Mydosh parameter lies within the range often associated with
vortex-glass behavior in
superconductors, a detailed analysis of DC magnetization, AC susceptibility, field dependence, and
magnetic memory effects demonstrates that the observed phenomena are not related to superconductivity. Instead, the data are consistent with glassy
magnetic freezing of interacting clusters. Compositional and structural analysis identifies covellite (CuS), an ubiquitous secondary phase in these intrinsically multiphase materials, as the primary origin of the observed behavior. Our results clarify the
magnetic origin of LK-99-related anomalies and highlight the importance of phase complexity in interpreting apparent superconducting signatures in this materials family.
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All authors Serafim Teknowijoyo, Domenico Napoletani, Vahan Nikoghosyan, Armen Gulian
Materials Science
AlphaDiffract: Automated Crystallographic Analysis of Powder X-ray Diffraction Data
Nina Andrejevic, Ming Du, Hemant Sharma et al. (+6 more)
Materials identification and structural understanding from powder X-ray diffraction (PXRD) data is a long-standing challenge in materials science, fundamental to discovering and characterizing novel materials. A prerequisite for full structure solution is the accurate determination of the
crystal lattice, including
lattice parameters and crystallographic
symmetries. Traditional methods for this are iterative and typically require expert input, and while existing deep learning approaches have shown promise, a robust, single-shot method for comprehensive
lattice determination from experimental data remains a key goal. Here, we introduce AlphaDiffract, a deep learning framework that achieves state-of-the-art performance in predicting the
crystal system, space group, and
lattice parameters directly from PXRD patterns. AlphaDiffract utilizes a 1D adaptation of the ConvNeXt architecture, a modern convolutional neural network that integrates key design principles from
transformers, coupled with dedicated prediction heads for each crystallographic property. The model is trained on the largest-to-date physics-based
dataset of over 31 million simulated diffraction patterns, generated by augmenting 312,267 curated structures from the ICSD and Materials Project databases. Crucially, it demonstrates strong generalization to experimental data, achieving 81.7%
crystal system accuracy and 66.2% space group accuracy on the RRUFF
dataset while additionally predicting all six
lattice parameters. By providing a unified model for rapid and accurate
lattice determination from PXRD data, AlphaDiffract represents a significant step forward in leveraging deep learning for high-throughput materials discovery.
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All authors Nina Andrejevic, Ming Du, Hemant Sharma, James P. Horwath, Aileen Luo, Xiangyu Yin, Michael Prince, Brian H. Toby, Mathew J. Cherukara
Materials Science · Cross-listed from physics.app-ph
Laser-Enhanced Contact Optimization in Silicon Photovoltaics: Mechanisms, Reliability, and Predictive Process Design
Donald Intal and Abasifreke U. Ebong
Laser-enhanced contact optimization (LECO) has emerged as an important method for simultaneously reducing contact resistivity and metallization-induced recombination in advanced crystalline silicon
solar cells, thereby enabling concurrent gains in fill factor and open-
circuit voltage, particularly in TOPCon devices. However, broader industrial transferability remains constrained by the need to preserve these gains within a narrow process window and by unresolved, architecture-dependent questions regarding the kinetic stability of some LECO-modified interfaces. LECO is therefore examined in this review as a coupled multiphysics process that links localized electrothermal activation and microstructural
evolution to device-level electrical signatures through an instantaneous regime map and a reliability classification based on time-dependent drift. A predictive workflow is outlined that couples transient electrothermal modeling with reduced state metrics, including effective
diffusion depth and local areal energy density, and propagates calibrated thresholds across the recipe space. The framework separates stable optimization from marginal activation and latent damage, while explaining why fine-line scaling and copper-containing contact stacks can tighten stability margins through current localization and
diffusion-barrier constraints. These insights provide a basis for reliability-aware process-window design and future digital-twin-assisted optimization of LECO for scalable, high-efficiency silicon photovoltaics.
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Strongly Correlated Electrons
Multistage spin correlations in the $s$ = 1/2 stuffed hyper-star lattice Li$_{2}$Cu$_{2}$(MoO$_{4}$)$_{3}$
J. Khatua, Taeyun Kim, G. Senthil Murugan et al. (+11 more)
Star lattice, which can be visualized as a honeycomb network with each vertex replaced by a triangle, provides a rare platform for realizing exotic
quantum states such as
quantum spin liquids and disorder-driven random-singlet (RS) states. Herein, we investigate the ground-state properties of the three-dimensional (3D) stuffed hyper-
star lattice Li$_2$Cu$_2$(MoO$_4$)$_3$, which exhibits a crossover from short-range
spin correlations to a disorder-driven RS-like state below $T^{*}\sim$15.8 K. Thermodynamic and microscopic measurements capture this crossover through a change in the power-law behavior of various observables, from $\sim T^{0.25}$ for $T > T^{*}$ to $\sim T^{-0.50}$ for $T < T^{*}$. Upon further cooling, a quasi-frozen state emerges near $T_{\rm f} = 0.32$ K, likely associated with weakly coupled
spin chains within the hyper-
star spin network. Our results underscore the crucial role of orphan
spins and weak residual interactions in stabilizing a disorder-driven
quantum-disordered state in 3D.
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All authors J. Khatua, Taeyun Kim, G. Senthil Murugan, S. M. Kumawat, C.-L. Huang, Yugo Oshima, Hiroyuki Nojiri, Gerald Morris, Sarah R. Dunsiger, Heung-Sik Kim, K. Sritharan, Shankar Mani, R. Sankar, Kwang-Yong Choi
Soft Condensed Matter
Where Humpty Dumpty Breaks: Geometry-Driven Fracture in Ellipsoidal Shells
Naoki Sekiya, Yuri Akiba, Kai Kageyama et al. (+3 more)
Fracture networks are ubiquitous in nature, spanning scales from millimeter-sized cracks in botanical peels to hundred-kilometer-long lineae on planetary satellites. The propagation of a crack is a complex, nonlinear phenomenon governed by the interplay of mechanical properties, rheological behavior, and system geometry. While fracture mechanics has long addressed structural failure, the relationship among fracture, elasticity, and nonlinear geometry has recently revived as a focal point in condensed matter and biophysics. However, a unified framework that systematically explains how surface geometry prescribes the transition between disparate fracture morphologies remains elusive. Here we show that shell
curvature provides a
geometric blueprint for fracture, governing the
evolution of complex crack networks through induced stress anisotropy. By internally pressurizing thin,
bilayer spheroidal shells, we demonstrate that a rich diversity of crack morphologies across lateral, longitudinal, and random orientations depends on the
curvature ratio between the pole and the equator. We find that these patterns arise from the nonlinear mechanics of the shell, which can be leveraged to effectively control crack growth. Our results establish a direct link between structural
curvature and fractures, providing a predictive framework that integrates nonlinear geometry with the classical Griffith and von Mises criteria. Beyond our model system, we find that the disparate fracture patterns observed in ripening muskmelons and in the icy crust of Europa follow the same
geometric principles. We expect that this unified understanding of crack morphogenesis will inform the design principles of novel functional materials that are resilient to fracture and provide insights into the mechanical performance of curved biological and geophysical architectures.
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All authors Naoki Sekiya, Yuri Akiba, Kai Kageyama, Hokuto Nagatakiya, Ryuichi Tarumi, Tomohiko G. Sano
Statistical Mechanics
The Fermi-Pasta-Ulam-Tsingou problem after 70 years: toward universal laws of thermalization in lattice systems in the thermodynamic limit
Weicheng Fu, Zhen Wang, Wei Lin et al. (+4 more)
The
Fermi–Pasta–Ulam–Tsingou (FPUT) problem provides a paradigmatic framework for understanding thermalization in weakly nonlinear many-body
Hamiltonian systems. This focused review summarizes major developments in near-integrable dynamics, wave resonances, and
phonon kinetic theory, emphasizing recent results on thermalization-time scaling in nonlinear
lattices. A coherent picture emerges in the thermodynamic limit based on the eigenmode properties of an appropriate integrable reference system. If the reference system has extended eigenmodes and the leading resonant or quasi-resonant processes form a sufficiently connected network, the thermalization time follows $T_{\mathrm{eq}}\propto g^{-2}$, where $g$ measures the effective deviation from integrability. This scaling is found broadly in ordered and weakly disordered
lattices and is robust to dimensionality, interaction potential, integrability-breaking mechanism, and multimode initial conditions. Identifying the correct integrable reference is essential; in some one-dimensional FPUT-type
lattices with cubic interactions, the nearby Toda
lattice, rather than the harmonic chain, provides the proper reference. If all reference eigenmodes are localized, spatial-overlap constraints progressively fragment low-order resonance networks as $g$ decreases, and thermalization becomes controlled by higher-order processes. Numerical studies reveal successive regimes $T_{\mathrm{eq}}\propto g^{-\gamma}$ with $\gamma=2,4,6$, together with weak system-size dependence. Whether this hierarchy persists asymptotically and whether a finite thermalization threshold exists remain open questions. We also discuss finite-size effects, strongly nonintegrable dynamics, heat transport, localization, and higher-dimensional
lattices.
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All authors Weicheng Fu, Zhen Wang, Wei Lin, Dahai He, Jiao Wang, Yong Zhang, Hong Zhao
Materials Science
Reliable and High Performance IGZO and In2O3 Transistors via Channel Capping
C. W. Cheng, J. Smith, K. Mashooq et al. (+13 more)
A device and process strategy for achieving reliable indium gallium zinc
oxide and indium
oxide transistors compatible with a 400oC BEOL thermal budget and without performance degradation is demonstrated by fully exploiting intrinsic
oxide material properties. An indium
oxide transistor with a novel amorphous In2O3 mixed with SiO2 capping layer exhibits a positive threshold voltage, high extrinsic saturation mobility 33.1 cm2/V.s ,and only a 5mV Vt shift after positive-bias stress at 3 MV/cm for 1000s at room temperature, superior to conventional SiO2 encapsulation.
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All authors C. W. Cheng, J. Smith, K. Mashooq, P. Solomon, R. Watters, T. Philicelli, D. Piatek, C. Lavoie, M. Hopstaken, L. Gignac, B. Khan, M. BrightSky, G. Gionta, P. Hashemi, V. Narayanan, M. M. Frank
Materials Science
Experimental Insights into the Limiting Mechanism of Vacancy Transport in Sodium Metal Anodes for Solid State Batteries
Ansgar Lowack, Rafael Anton, Bingchen Xue et al. (+4 more)
Ceramic solid-state batteries with sodium (Na) metal electrodes promise enhanced safety and energy density compared to contemporary secondary batteries. However, the critical delamination of the Na metal electrode during discharge - when vacancies accumulate at the Na/ceramic interface - remains to be understood and avoided. The study investigates the underlying mechanism by applying a linear current ramp between two Na metal electrodes separated by a ceramic solid electrolyte to provoke vacancy buildup. Above a critical current density $j_\mathrm{crit}$ the anode voltage no longer increases linearly but in an exponential fashion. Arrhenius analysis of $j_\mathrm{crit}(T)$ for the three solid electrolytes $\mathrm{Na_{1.9}Al_{10.67}Li_{0.33}O_{17}}$, $\mathrm{Na_{3.4}Zr_2Si_{2.4}P_{0.6}O_{12}}$, and $\mathrm{Na_5SmSi_4O_{12}}$ yields an activation energy $E_\mathrm{A}$ of $0.13$ to $0.15\,\mathrm{eV}$. This exceeds the activation energy of $0.053\,\mathrm{eV}$ for the diffusive vacancy migration in bulk Na significantly. Further, $E_\mathrm{A}$ is insensitive to anode microstructure variation. Both observations rule out bulk
diffusion as the transport bottleneck. A thin tin-sodium
alloy interlayer lowers $E_\mathrm{A}$ to $(0.10\pm0.01)\,\mathrm{eV}$, implicating interfacial thermodynamics as rate-limiting. Sodiophilic, Na-conducting interlayers and low-tension interfaces emerge as key pathways to stable, high-rate Na-SSBs at practical stack pressures.
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All authors Ansgar Lowack, Rafael Anton, Bingchen Xue, Kristian Nikolowski, Cornelius Dirksen, Mareike Partsch, Alexander Michaelis
Statistical Mechanics
Internal stress drives ferromagnetic-like ordering in networks of proliferating bacteria
Nicola Pellicciotta, Luca Angelani and Roberto Di Leonardo
Proliferation is a defining feature of life. Through growth, division, and death, living systems consume energy and inject mass, breaking conservation laws and driving collective phenomena from biofilm formation to embryonic development. Yet, while active matter physics has advanced our understanding of self-propelled
agents, quantitative frameworks for proliferating systems are still emerging, and most work focuses on simplified settings. Here, we study E.coli bacteria growing inside a network of single-file microchannels as a minimal model of structured environments. Competition for free volume drives the spontaneous emergence of coherent growth patterns that persist across generations but vanish when the channel links exceed the typical
cell size at birth. Despite the strongly out-of-
equilibrium character of the dynamics, the observed phenomenology can be quantitatively captured by an effective
equilibrium description in which the flow state at each node is represented by a
spin variable with
ferromagnetic interactions. Simulations of growing elastic
cells show that this coupling arises from internal stress accumulated at network nodes due to dynamical constraints. Our results reveal a surprising correspondence between proliferating active matter and
equilibrium statistical mechanics, highlighting open fundamental questions and offering a first step toward describing growth phenomena in real-world complex environments.
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Superconductivity
Correlation-driven enhancement of pairing in a nematic Hund's metal
Angelo Valli and Laura Fanfarillo
Superconductivity and nematicity coexist in the phase diagram of many correlated systems, including iron-based
superconductors. We investigate how Hund-driven correlations reshape
boson-mediated superconductivity in a multiorbital nematic metal. We find that dynamical correlation effects beyond a quasiparticle-only description are essential to capture the robustness of superconductivity in the Hund regime. In the nematic phase, Hund correlations simultaneously enhance the orbital differentiation of the superconducting gaps and inhibit the most extreme nematic-driven orbital polarization and coherence collapse that would otherwise suppress pairing at strong coupling. A controlled cutoff analysis reveals a nontrivial, orbital-dependent buildup of the gaps, indicating that different frequency windows of the correlated spectrum contribute unevenly to pairing in the nematic Hund regime. This implies that pairing mechanisms with different characteristic
boson energies can lead to distinct gap structures and trends.
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Quantum Gases
Occupation-selective topological pumping from Floquet gauge fields
Wenjie Liu, Ching Hua Lee and Zhoutao Lei
Topological pumping is conventionally governed by single-particle band
topology. Here we show that promoting tunneling to a dynamical, occupation-conditioned variable fundamentally reshapes this paradigm, leading to occupation-selective topological pumping. In a periodically driven one-dimensional superlattice with density-dependent hopping, two-body bound states (doublons) acquire Chern numbers distinct from those of single particles and exhibit quantized transport even when the single-particle pump is trivial, including counter-propagating responses. We identify a dynamical-gauge-field mechanism that induces topological phase transitions in the bound-state sector absent from the single-particle spectrum. Furthermore, the gauge field concentrates Berry
curvature into sharply localized resonant regions without compromising adiabatic quantization. A Floquet realization with ultracold atoms is proposed to realize such occupation-selective pumping. Our results reveal a mechanism for occupation-selective topological responses that can persist across higher-occupancy bound states.
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Strongly Correlated Electrons
Fermiology, charge transfer energy, and robust paramagnons in high-$T_c$ cuprate superconductors
Maciej Fidrysiak
Copper-
oxide high-temperature (high-$T_c$)
superconductors host robust paramagnon excitations whose propagation energies are insensitive to hole concentration and correlate with maximal measured superconducting transition temperatures. Given variation of electronic structure across (and within) cuprate families, elucidation of the relationship between microscopic parameters relevant to high-$T_c$ superconductivity and paramagnon dynamics remains a key challenge to theory. Employing canonical Hubbard- and $t$-$J$-$U$ models of a $\mathrm{CuO_2}$ plane, we relate robust paramagnon energies to high-$T_c$ fermiology (via the ratio $r \equiv t^\prime/|t|$ of next-nearest- to nearest-neighbor hopping integrals) and charge transfer energy, $\Delta_\mathrm{CT}$. It is shown that variation of $r$ and $\Delta_\mathrm{CT}$ between materials has an opposite effect on paramagnon energy, rationalizing comparable bandwidth of
magnetic excitations across multiple cuprates. Utilizing empirical values of $r$ and $\Delta_\mathrm{CT}$ as input to theory, we address
magnetic dynamics in Bi-cuprate family representatives with up to three $\mathrm{CuO_2}$ planes, and demonstrate quantitative (within $6\,\%$ margin) agreement of calculated paramagnon energies with experiment. Our work offers a route toward quantitative control of robust paramagnon physics in strongly-correlated electron systems.
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Mesoscale and Nanoscale Physics
Comment on 'Observation of Shapiro Steps in the Charge Density Wave State Induced by Strain on a Piezoelectric Substrate'
D.Yu. Saltykova, M.V. Nikitin, V.Ya. Pokrovskii et al. (+5 more)
In their Letter Fujiwara et al. (10.48550/arXiv.2511.09888. 2025) report a high-quality experiment demonstrating the synchronization of the CDW sliding in NbSe3 whiskers (nanowires) with surface acoustic waves (SAWs). The SAWs are induced in the conventional LiNbO3 piezoelectric substrates through application of rf voltage to an interdigital transducer (IDT). When a SAW mode is excited, Shapiro steps (ShSs) appear on the I-V curves, while no ShSs are observed when the frequency is shifted from the resonance. This gives clear evidence of synchronization of the CDW with the acoustic modes.
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All authors D.Yu. Saltykova, M.V. Nikitin, V.Ya. Pokrovskii, S.G. Zybtsev, V.V. Kolesov, V.V. Kashin, I.E. Kuznetsova, I.A. Nedospasov
Mesoscale and Nanoscale Physics
Tunable Goos–Hänchen shifts and group delay time in single-barrier silicene
Youssef Fattasse, Hocine Bahlouli, Clarence Cortes et al. (+2 more)
We investigate the Goos–Hänchen (GH) shifts and group delay time of Dirac
fermions traversing a rectangular electrostatic potential barrier in silicene. By analyzing their dependence on the incident angle, barrier height, barrier width, and incident energy, we demonstrate that the GH shifts exhibit pronounced oscillations arising from
quantum interference within the barrier region. The amplitude and number of oscillation peaks increase with increasing energy, barrier width, and incidence angle, resulting in enhanced lateral beam displacement. Meanwhile, the group delay time exhibits resonant features associated with the formation of quasi-bound states, increasing with barrier width, energy, and incidence angle, while decreasing with increasing barrier height. These results clarify how barrier-induced
quantum interference controls both the lateral and temporal dynamics of Dirac
fermions in silicene, highlighting the potential role of electrostatic barriers in enabling tunable transport in two-dimensional Dirac materials.
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All authors Youssef Fattasse, Hocine Bahlouli, Clarence Cortes, David Laroze, Ahmed Jellal