Strongly Correlated Electrons
Hidden Density-Wave Instability in the Trimer Ruthenate Ba$_4$Ru$_3$O$_{10}$
Gang Cao, Hengdi Zhao, Adrienne Bond et al. (+9 more)
We report a hidden density-wave instability in the trimer-based ruthenate Ba4Ru3O10, previously regarded as a pure antiferromagnet with a phase transition at TA=100 K. This transition is manifested in
lattice parameters, transport, thermodynamics, and
magnetic susceptibility, yet remains remarkably insensitive to
magnetic fields up to at least 14 T, indicating an electronically driven reconstruction. At much lower temperatures T*= 20 K, charge transport becomes strongly nonlinear, exhibiting distinct depinning thresholds, negative differential resistance, pronounced current- and frequency-dependence, and slow collective dynamics in the Hertz range. While each feature is characteristic of density-wave transport, their simultaneous occurrence in an
antiferromagnetic oxide is unprecedented. All nonlinear signatures vanish upon only 3% Ir substitution, which preserves the
crystal structure and insulating state, ruling out Joule heating or extrinsic artifacts. The wide separation between the electronic reconstruction at TA and the emergence of nonlinear dynamics at T* identifies Ba4Ru3O10 as a rare correlated system hosting a strongly pinned collective electronic state intertwined with antiferromagnetism.
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All authors Gang Cao, Hengdi Zhao, Adrienne Bond, Tristan R. Cao, Gabriel Schebel, Arabella Quane, Yifei Ni, Yu Zhang, Logan Wall, Rahul Nandkishore, Pedro Schlottmann, Feng Ye
Materials Science · Cross-listed from quant-ph
Quantum Algorithm Framework for Phase-Contrast Transmission Electron Microscopy Image Simulation
Sean D. Lam and Roberto dos Reis
We present a
quantum algorithmic framework for simulating phase-contrast transmission electron microscopy (CTEM) image formation using a fault-tolerant, gate-based
quantum circuit model. The electron wavefield on an $N\times N$ grid is amplitude-encoded into a $2\log_2 N$-
qubit register. Free-space propagation and objective-lens aberrations are implemented via two-dimensional
quantum Fourier transforms (QFTs) and diagonal phase operators in reciprocal space, while specimen interaction is modeled under the weak phase object approximation (WPOA) as a position-dependent phase grating. We validate projected potentials, contrast transfer function (CTF) behavior, and image contrast trends against classical multislice simulations for MoS$_2$ over experimentally relevant parameters, and provide resource estimates and key assumptions that determine end-to-end runtime. While extracting complete $N\times N$ intensity images requires $O(N^2/\epsilon^2)$ measurements that preclude advantage for full-image reconstruction, the framework enables
quantum advantage for tasks requiring
Fourier-space queries, global image statistics, or phase-coherent observables inaccessible to classical intensity-only detection. This framework provides a physics-grounded mapping from CTEM theory to
quantum circuits and establishes a baseline for extending toward full multislice and inelastic scattering models.
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Materials Science
Eco-Friendly Supercapacitor Architecture Based on Cotton Textile Waste and Biopolymer-Based Electrodes
Luis Torres Quispe, Clemente Luyo Caycho, Javier Quino-Favero et al. (+2 more)
This study presents an eco-friendly and bio-based symmetric supercapacitor using cotton textile waste-derived hydrogels as electrolytes and chitosan-based carbon electrodes as metal-free charge-storage components. Cotton-derived hydrogels were synthesized via an alkaline dissolution-gelation route and modified with ammonium thiocyanate (NH4SCN) to enhance ionic conductivity. The ionic modification increased the hydrogel conductivity from 17.1 to 37.8 mS cm^-1, confirming a nearly twofold improvement in ion transport efficiency. The resulting hydrogel exhibited improved thermal stability, homogeneous ionic transport, and strong
polymer-ion interactions confirmed by FTIR and TGA analyses. In a symmetric device, the ion-modified hydrogel enables reduced equivalent series resistance, faster charge-transfer kinetics, and a short time constant (tau = 3.2 s), comparable to commercial energy-storage systems. After 1000 cycles, the device exhibits a 12.3% increase in specific capacitance, confirming stable proof-of-concept operation. Cycling leads to a moderate increase in R_ESR (18 to 22 ohm) and tau (3.2 to 4.1 s), indicating slower charge-ion redistribution. Notably, this R_ESR includes the contribution of the test-
cell setup; in compact coin-type configurations, the resistance would be considerably lower. EIS reveals a concurrent rise in interfacial resistive terms, consistent with post-cycling hydrogel darkening and FTIR evidence of Fe-SCN coordination, suggesting that resistance buildup mainly originates from minor Fe-SCN interactions when the expelled
liquid reaches the stainless-steel collector, rather than from loss of capacitive functionality. Overall, these results demonstrate the viability of cotton waste-derived hydrogels and chitosan-based electrodes as sustainable components for green energy storage, offering a recyclable and eco-friendly alternative to conventional systems.
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All authors Luis Torres Quispe, Clemente Luyo Caycho, Javier Quino-Favero, Silvia Ponce, Abel Gutarra
Disordered Systems and Neural Networks · Cross-listed from q-bio.PE
Spatiotemporal noise stabilizes unbounded diversity in strongly-competitive communities
Amer Al-Hiyasat, Daniel W. Swartz, Jeff Gore et al. (+1 more)
Classical ecological models predict that diverse communities should be unstable, presenting a central challenge to explaining the stable biodiversity seen in nature. We revisit this long-standing problem by extending the generalized Lotka-Volterra model to include both spatial structure and environmental fluctuations across space and time. We find that neither space nor environmental noise alone can resolve the tension between diversity and stability, but that together they permit arbitrarily many species to stably coexist in a sufficiently large system, despite strongly disordered competitive interactions. We analytically characterize the noise-induced transition to coexistence, showing that spatiotemporal noise drives power-law abundance fluctuations, leading to an anomalous scaling of moments known empirically as Taylor's law. At the metacommunity level, this manifests as an emergent sublinear self-inhibition that stabilizes diversity and renders the interaction disorder irrelevant in the high-diversity limit. Spatiotemporal noise thus provides a novel resolution to the diversity-stability paradox and a generic mechanism by which complex communities can persist.
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All authors Amer Al-Hiyasat, Daniel W. Swartz, Jeff Gore, Mehran Kardar
Statistical Mechanics
Evolutionary design of thermodynamic logic gates and their heat emission
Stephen Whitelam
Landauer's principle bounds the heat generated by logical operations, but in practice the thermodynamic cost of computation is dominated by the control systems that implement logic. CMOS gates dissipate energy far above the Landauer bound, while laboratory demonstrations of near-Landauer erasure rely on external measurement or feedback systems whose energy costs exceed that of the logic operation by many orders of magnitude. Here we use simulations to show that a genetic
algorithm can program a thermodynamic computer to implement logic operations in which the total heat emitted by the control system is of a similar order of magnitude to that of the information-bearing degrees of freedom. Moreover, the computer can be programmed so that heat is drawn away from the information-bearing degrees of freedom and dissipated within the control unit, suggesting the possibility of computing architectures in which heat management is an integral part of the program design.
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Strongly Correlated Electrons
Exact columnar dimer ground state and quantum phase transitions in a frustrated coupled spin ladder model
Manas Ranjan Mahapatra and Rakesh Kumar
We study a
spin-half frustrated coupled ladder system, in which ladders with leg, rung, and diagonal interactions are linked via nearest-neighbor coupling. By introducing a leg-symmetric inter-ladder interaction that connects the left-to-left and right-to-right legs of adjacent ladders, the model is found to possess an exact dimer ground state, characterized by a product of two-
spin singlets forming a columnar dimer phase. We analyze this model using bond-operator mean-field theory (BOMFT) and the density
matrix renormalization group (DMRG) to probe the phase transitions that occur as one traverses the coupling space. The BOMFT reveals three distinct phases: a double-stripe ordered phase, a Néel ordered phase, and a
quantum disordered dimerized phase. The critical points for the transitions are at $ J_1 = -0.81 $ (double-stripe to dimerized) and at $ J_1 = 2.81 $ (dimerized to Néel phase). Further, the DMRG results corroborate the exact ground state and refine the critical points to $ J_1 = -0.79 $ and $ J_1 = 2.29 $ for the respective transitions. Additionally, another transition is identified as the Néel order vanishes for $ J_1 \ge 4.5 $. The model can alternatively be represented as a network of orthogonal zigzag and fully frustrated
spin ladders, offering a structural framework conducive to
quantum materials engineering.
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Mesoscale and Nanoscale Physics
Dynamical metastability and transient topological magnons in interacting driven-dissipative magnetic systems
Vincent P. Flynn, Lorenza Viola and Benedetta Flebus
Metastability, i.e., partial relaxation to long-lived, quasi-stationary states before true asymptotic
equilibrium sets in, emerges ubiquitously in classical and
quantum dynamical systems as a result of timescales separation. In open
quantum systems, an intrinsically nonequilibrium analogue, dynamical metastability, can originate from the spectral geometry of a non-Hermitian operator. In noninteracting models, this mechanism produces boundary-sensitive anomalous relaxation, transient amplification, and topologically mandated long-lived edge modes, all of which are enhanced as system size grows. Here we extend dynamical metastability into the nonlinear, interacting regime and identify
magnetic heterostructures as a natural platform for its exploration. We introduce an interacting
spin Lindbladian whose linearized
magnon dynamics map onto a dynamically metastable Hatano-Nelson chain, and show that dynamical metastability in the noninteracting limit seeds genuinely nonlinear phenomena, including size-dependent
spin dipping and anomalous attraction to unstable
equilibria. Long-lived edge states associated to topologically mandated Dirac
bosons persist under nonlinearities and disorder. We further analyze the magnetization dynamics in
magnetic multilayers within the classical Landau-Lifshitz-Gilbert-Slonczewski framework, identifying Dzyaloshinskii-Moriya interaction, nonlocal damping, and
spin-transfer torque as control parameters governing bulk-boundary stability mismatch and band
topology. While all the distinctive dynamical phenomena previously identified reappear in this experimentally relevant setting, the LLGS framework also supports multistability and limit cycles that are absent in the
quantum model. Our results constitute the first systematic study of dynamical metastability in nonlinear dynamics, directly relevant to
spin-torque oscillator arrays, magnonic devices, and beyond.
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Statistical Mechanics · Cross-listed from quant-ph
Entanglement in quantum spin chains is strictly finite at any temperature
Ainesh Bakshi, Soonwon Choi and Saúl Pilatowsky-Cameo
Entanglement is the hallmark of
quantum physics, yet its characterization in interacting many-body systems at thermal
equilibrium remains one of the most important challenges in
quantum statistical physics. We prove that the Gibbs state of any
quantum spin chain can be exactly decomposed into a mixture of
matrix product states with a bond dimension that is independent of the system size, at any nonzero temperature. As a consequence, the Schmidt number, arguably the most stringent measure of bipartite
entanglement, is strictly finite for thermal states, even in the thermodynamic limit. Our decomposition is explicit and is accompanied by an efficient classical
algorithm to sample the resulting
matrix product states.
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Strongly Correlated Electrons
Adaptive Pseudoboson Density-Matrix Renormalization Group for Dilute 2D Systems
Fabian J. Pauw, Thomas Köhler, Ulrich Schollwöck et al. (+1 more)
Simulating strongly correlated systems in two dimensions is notoriously challenging due to rapid
entanglement growth and frustration. Here, we introduce the adaptive projected-purified pseudoboson density-
matrix renormalization group (A3P-DMRG) tailored to explore the ground states of dilute
lattice models. The method compresses cluster
Hilbert spaces by retaining only the most probable low-occupation Fock states, identified via probabilistic bounds and refined through a self-consistent mean-field basis optimization. We demonstrate that A3P-DMRG is advantageous in low-filling and weak-coupling regimes for large system sizes where conventional DMRG struggles. This establishes the method as a versatile tool for studying dilute
quantum many-body systems relevant to ultra-cold atom
quantum simulators, photonic
lattices, Moiré materials and
quantum chemistry.
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All authors Fabian J. Pauw, Thomas Köhler, Ulrich Schollwöck, Sebastian Paeckel
Materials Science
Room Temperature RF Sputtering of Mixed Ionic and Electronic Conductor Nd2Ni0.8Cu0.2O4+d films
N. Coppola, M. Paone, H.S. Ur Rehman et al. (+8 more)
Lowering the operating temperature of Solid
Oxide Fuel
Cells (SOFCs) is essential for improving durability and enabling large scale commercialization. Mixed ionic-electronic conductors (MIECs) of the Ruddlesden-Popper family, such as Nd$2$Ni${1-x}$Cu$x$O${4+\delta}$ (NNCO), offer attractive cathode properties due to their high oxygen transport and favourable defect chemistry. In this work, we investigate the fabrication of Nd$2$Ni${0.8}$Cu${0.2}$O${4+\delta}$ thin films using a room temperature RF sputtering process followed by moderate temperature annealing. To simplify deposition, a single stoichiometric target was employed, despite the compositional challenges posed by elements with different sputtering yields. We examine the effect of sputtering power density on phase formation and film stoichiometry through X-ray diffraction, Rutherford Backscattering Spectrometry, Energy Dispersive X-ray Spectroscopy, and temperature dependent resistivity measurements. Increasing the sputtering power density strongly reduces the presence of spurious phases and promotes stabilization of the desired n=1 Ruddlesden-Popper phase. Films deposited at 230 W (3.1 W cm$^{-2}$) exhibit a predominant NNCO structure, elemental ratios close to nominal composition, and resistivity values consistent with bulk materials. These findings demonstrate that high power sputtering combined with ex situ annealing enables the production of NNCO thin films suitable for SOFC cathodes. The results support the potential of PVD based approaches for scalable fabrication of advanced SOFC components.
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All authors N. Coppola, M. Paone, H.S. Ur Rehman, S. Scarnicci, G. Carapella, A. Guarino, M. Tkalcevic, L. Calcagnile, G. Quarta, A. Galdi, L. Maritato
Materials Science
Tuning Optoelectronic Properties and Photoelectrochemical Performance of e̱ta}-TaON via Vanadium Doping
Mirabbos Hojamberdiev, Ronald Vargas, Lorean Madriz et al. (+7 more)
The application of beta-TaON for
solar-driven water splitting is hindered by limitations in phase purity, stoichiometry, crystallinity, visible-light absorption, carrier mobility, and high recombination rates. This study investigates the impact of vanadium doping (0-25 at.% V) on the structural, optoelectronic, and photoelectrochemical properties of beta-TaON using both experimental and density functional theory (DFT) approaches. Phase-pure beta-TaON is retained up to 10 at.% V, beyond which secondary phases (Ta2O5 and VN) form, indicating a threshold of ~10 at.% under the applied synthesis conditions. All samples exhibit a porous microstructure. Increasing vanadium content induces a
redshift in the absorption edge, reducing the bandgap from 2.72 eV (undoped) to 2.38 eV at 25 at.% V for the main beta-TaON phase, in agreement with DFT results. X-ray photoelectron spectroscopy confirms substitutional incorporation of V5+ for Ta5+ in the beta-TaON
lattice. DFT calculations reveal reduced electron effective mass, enhanced n-type conductivity, and favorable band edge shifts enabling spontaneous overall water splitting at <=10 at.% V. Photoelectrochemical measurements show improved photocurrent and more negative onset potentials for 5-10 at.% V, while higher V doping degrades performance due to phase segregation, which likely increases recombination and hinders interfacial charge transport. Vanadium doping (<=10 at.% V) is an effective strategy for tuning the electronic structure and enhancing the optical properties and photoelectrochemical performance of beta-TaON.
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All authors Mirabbos Hojamberdiev, Ronald Vargas, Lorean Madriz, Dilshod Nematov, Ulugbek Shaislamov, Hajime Wagata, Yuta Kubota, Kunio Yubuta, Katsuya Teshima, Nobuhiro Matsushita
Disordered Systems and Neural Networks · Cross-listed from cs.CL
Semantic Chunking and the Entropy of Natural Language
Weishun Zhong, Doron Sivan, Tankut Can et al. (+2 more)
Humans and large
language models can predict next letter or word from its prior context much better than random guessing, indicating strong redundancy of
language viewed as a
stochastic process. Quantitatively this redundancy was estimated by Shannon to be around 80%, which means that every letter of a printed English text conveys approximately 1 bit of information and not 4.8 bits that 27 letters (including spaces) could potentially carry. This estimate was later confirmed by using autoregressive
token probabilies computed by large
language models. However, the statistical organization of
language that give rise to such a large redundancy remains unclear. Here we introduce a statistical framework of
language linking its redundancy to the hierarchical semantic organization of text. To this end, we use large
language models to recursively segment any given text into semantically coherent chunks, inducing a “semantic tree” that spans the whole range of text organization, beginning from its main idea to individual
tokens (words). For a large corpus of texts of a particular type, say fiction stories, the resulting ensemble of semantic trees is characterized by specific statistical regularities, giving rise to a “structural”
entropy rate defined in this study. Surprisingly, we discovered that for several
datasets considered in this work, semantic tree
entropy rate was quite close to LLM-measured quantity and exhibited a similar trend across corpus. In particular, simpler texts like children stories exhibit lower branching in their semantic trees and correspondingly lower
entropy rates, whereas fiction and poetry exhibit progressively larger branching factors and greater
entropy rates. These results suggest that hierarchical semantic organization of texts is an important factor in their overall information transmission rates.
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All authors Weishun Zhong, Doron Sivan, Tankut Can, Mikhail Katkov, Misha Tsodyks
Quantum Gases
Matter-induced plaquette terms in a $\mathbb{Z}_2$ lattice gauge theory
Matjaž Kebrič, Fabian Döschl, Umberto Borla et al. (+4 more)
Lattice gauge theories (LGTs) provide a powerful framework for studying confinement, topological order, and exotic
quantum matter. In particular, the paradigmatic phenomenon of confinement, where dynamical matter is coupled to gauge fields and forms bound states, remains an open problem. In addition, LGTs can provide low-energy descriptions of
quantum spin liquids, which is the focus of ongoing experimental research. However, the study of LGTs is often limited theoretically by their numerical complexity and experimentally in implementing challenging multi-body interactions, such as the plaquette terms crucial for the realization of many exotic phases of matter. Here we investigate a $(2+1)$D $\mathbb{Z}_2$ LGT coupled to hard-core bosonic matter featuring a global U(1)
symmetry, and show that dynamical matter naturally induces sizable plaquette interactions even in the absence of explicit plaquette terms in the
Hamiltonian. Using a combination of density
matrix renormalization group simulations and neural
quantum state calculations up to a system size of $20 \times 20$, we analyze the model across different fillings and electric field strengths. At small coupling strength, we find a large plaquette expectation value, independent of system size, for a wide range of fillings, which decreases in the presence of stronger electric fields. Furthermore, we observe signatures of a confinement-deconfinement transition at weak coupling strengths. Our results demonstrate that dynamical U(1) matter can induce complex multi-body interactions, suggesting a natural route to the realization of strong plaquette terms and paving the way for realizing a topological
quantum spin liquid protected by a large gap.
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All authors Matjaž Kebrič, Fabian Döschl, Umberto Borla, Jad C. Halimeh, Ulrich Schollwöck, Annabelle Bohrdt, Fabian Grusdt
Materials Science
Disorder viscosity correction approach to calculate spinodal temperature and wavelength
Simon Divilov, Hagen Eckert, Nico Hotz et al. (+2 more)
Spinodal decomposition, a key mechanism to microstructure formation in materials, has long posed challenges for predictive modeling, due to the need for parameter-free approaches that accurately capture local energy landscapes. In this work, we propose an approach to predict spinodal behavior by introducing a disorder viscosity correction to bulk free energies computed from finite, small, representative
cells. We approximate the energy penalty required to transition into a disordered state to enable the stabilization of locally concave bulk free energy regions - essential for interface formation - while suppressing long-range concentration fluctuations. This approximation circumvents the complexity of full ab initio parameterization of interfacial properties and is well-suited for high-throughput and machine-learning frameworks. Our approach captures the necessary physics underpinning spinodal kinetics, offering a scalable route to predict spinodal regions in compositionally complex and high-
entropy materials.
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All authors Simon Divilov, Hagen Eckert, Nico Hotz, Xiomara Campilongo, Stefano Curtarolo
Materials Science
Diamond-to-graphite transformation under hypersonic impact
Abhijit Biswas, Aniket Mote, Rajib Sahu et al. (+19 more)
Diamond to graphite transformation is a complex kinetically driven process which has been studied under various conditions for its fundamental importance. We report the transformation of diamond embedded ceramic
matrix composites during hypersonic impact. Diamond particles embedded in cubic boron nitride
matrix provide a superhard composite that was subjected to high impact collisions of metal projectiles travelling at speeds reaching Mach 8.45. Our observations suggest that the energy absorption and fracture of the composite is primarily enabled via the phase change of diamond into graphite. Characterization of the impact-fractured composite shows transformed diamond particles and provides details of the shock-induced phase transformation and the nature of diamond-graphite interfaces formed during rapid phase change. The study provides new understanding of phase transformation of diamond under extreme conditions.
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All authors Abhijit Biswas, Aniket Mote, Rajib Sahu, Marcelo Lopes Pereira Junior, Shuo Yang, Sudaice Kazibwe, Jishnu Murukeshan, Raphael Benjamim de Oliveira, Guilherme da Silva Lopes Fabris, Shreyasi Chattopadhyay, Gelu Costin, Jianhua Li, Robert Vajtai, Ching-Wu Chu, Lizhong Lang, Yu Zou, Liangzi Deng, Tobin Filleter, Douglas Soares Galvão, Christian Kübel, Thomas E Lacy Jr, Pulickel M. Ajayan
Strongly Correlated Electrons · Cross-listed from physics.chem-ph
Nuclear gradients from auxiliary-field quantum Monte Carlo and their application in geometry optimization and transition state search
Jo S. Kurian, Ankit Mahajan and Sandeep Sharma
In this article, we present a method for computing accurate and scalable
nuclear forces within the phaseless auxiliary-field
quantum Monte Carlo (AFQMC) framework. Our approach leverages automatic differentiation of the energy functional to obtain
nuclear gradients at a computational cost comparable to that of energy evaluation. The accuracy of the method is validated against finite difference calculations, showing excellent agreement. We then explore several machine learning (ML) strategies for learning noisy AFQMC data. These ML potentials are subsequently used to perform geometry optimizations and nudged elastic band (NEB) calculations, successfully identifying the transition state of the formamide-formimidic acid tautomerization. The resulting transition state geometry and barrier heights are in close agreement with coupled-cluster reference values. This work paves the way for highly accurate geometry optimization, molecular dynamics, or reaction path calculations.
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Quantum Gases
Absorption imaging of quantum gases near surfaces using incoherent light
Julia Fekete, Poppy Joshi, Peter Krüger et al. (+1 more)
We introduce an absorption imaging technique for ultracold gases that suppresses interference fringes and coherence-induced artifacts by reducing the transverse spatial coherence of the imaging light. The method preserves the narrow spectral bandwidth required for resonant absorption imaging and is implemented as a modular extension to standard imaging setups using a rotating diffuser. We demonstrate tunability of the illumination light's coherence without modifying the imaging optics. Using this approach, we achieve reliable imaging of ultracold atomic clouds in micron-scale proximity to complex surfaces, where standing waves, edge diffraction, and speckle severely limit conventional absorption imaging.
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All authors Julia Fekete, Poppy Joshi, Peter Krüger, Fedja Oručević
Statistical Mechanics
Accuracy Comes at a Cost: Optimal Localisation Against a Flow
Till Welker and Patrick Pietzonka
How much work does it cost for a propelled particle to stay localised near a stationary target, defying both thermal noise and a constant flow that would carry it away? We study the control of such a particle in finite time and find optimal protocols for time-dependent swim velocity and diffusivity, without feedback. Accuracy, quantified via the mean squared deviation from the target, and energetic cost turn out to be related by a trade-off, which complements the one between precision and cost known in
stochastic thermodynamics. We show that accuracy better than a certain threshold requires active driving, which comes at a cost that increases with accuracy. The optimal protocols have discontinuous swim velocity and diffusivity, switching between a passive drift state with vanishing diffusivity and an active propulsion state. This study highlights how a time-dependent diffusivity enhances optimal control and sets
benchmarks for cost and accuracy of artificial self-propelled particles navigating noisy environments.
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Mesoscale and Nanoscale Physics
Non-chiral ephemeral edge states and cascading of exceptional points in the non-reciprocal Haldane model
Aditi A. Prabhudesai, H. S. Chhabra and Suraj S. Hegde
We study a variant of the Haldane honeycomb model that has non-reciprocal hoppings between the next-nearest neighbours. The system on a
torus hosts time-reversal
symmetry protected exceptional rings(ER) in the spectrum. The ERs act as Berry-
curvature flux tubes i.e the Berry
curvature is non-zero only inside the ERs. The system on a cylinder having zig-zag boundaries (and transverse momentum $k_x$) hosts edge-states that have zero group velocity at $k_x=\pi$ and are therefore `non-
chiral'. The edge states undergo a bifurcation transition at an exceptional point(EP)in the BZ and delocalise into the bulk. As the non-reciprocity is increased, the bulk states that are approaching each other are converted into pairs of EPs due to non-Hermiticity. As the non-reciprocity is further increased, there is a `Russian doll'-like nested proliferation of pairs of EPs, leading to an EP-cascade. The proliferation of EPs takes place only at specific values of the non-hermiticity parameter, leading to a step-like structure in the EP-pair density when plotted as a function of non-Hermiticity. Further, using wave packet dynamics, we find a tunable regime where the non-
chiral edge states can be dynamically stabilised for large timescales. The `self-acceleration' term in the equations of motion tends to diffuse the wave packets into the bulk, thus making them `ephemeral edge states'. But we find that for small non-hermiticity, the edge localisation is stabilised until late times for sufficiently wider wave packets. Thus, we have brought forth an intriguing phenomenology of the exceptional phase of the non-reciprocal Haldane model, which may bear direct relevance for systems such as disordered Kitaev honeycomb model, wherein such ERs have been predicted.
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Strongly Correlated Electrons
Resonant level model coupled to a Sachdev-Ye-Kitaev bath
Anastasia Enckell and Stefan Kehrein
We investigate the non-
equilibrium dynamics of a resonant level model coupled to a strongly interacting electron bath modeled by a Sachdev-Ye-Kitaev (SYK) model. Different from the well-investigated case of a structureless non-interacting
Fermi gas bath leading to a temperature-independent exponential decay of the
impurity orbital occupation, we find a temperature-dependent oscillatory decay. We attribute this difference to the lack of quasiparticles in the SYK model, which is reflected in its singular density of states at the
Fermi level. Our results are exact and can be obtained analytically by mapping to a suitably structured
Fermi gas bath as an ancillary model for the SYK bath.
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Statistical Mechanics · Cross-listed from physics.comp-ph
An Always-Accepting Algorithm for Transition Path Sampling
Magdalena Häupl, Sebastian Falkner, Peter G. Bolhuis et al. (+2 more)
We present a one-way shooting
algorithm for transition path sampling that accepts every proposed trajectory, yet samples the correct transition path ensemble for systems with overdamped
stochastic dynamics. The method is based on two key elements: a procedure to propose trajectories that are always reactive, and a reweighting scheme that corrects for the bias introduced by always accepting the proposed paths. This approach significantly improves the efficiency of transition path sampling by eliminating the cost associated with generating trajectories that are then rejected. We demonstrate the performances of the
algorithm by investigating the formation of CO$_2$ clathrate hydrates along different reaction mechanisms, showing that the increased efficiency allows proper sampling of the formation of crystalline hydrates at temperatures and pressures that are difficult to access with conventional schemes.
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All authors Magdalena Häupl, Sebastian Falkner, Peter G. Bolhuis, Christoph Dellago, Alessandro Coretti
Quantum Gases
Emergent aperiodicity in Bose-Bose mixtures induced by spin-dependent periodic potentials
Abid Ali, Pei Zhang, Hiroki Saito et al. (+1 more)
We study the ground-state and low-lying metastable phases of repulsive binary Bose-Einstein condensates confined in twisted,
spin-dependent periodic optical
lattices. For balanced mixtures, weak intercomponent interactions yield a fourfold momentum-space
symmetry dictated by the
lattice geometry. Increasing the coupling strength leads to the emergence of additional momentum peaks that combine with the
lattice-induced structure to produce an eightfold rotationally symmetric pattern, signaling quasicrystalline order. At intermediate interactions, global phase separation suppresses this quasicrystalline state; however, at stronger coupling, local phase separation gives rise to a long-lived metastable phase in which the eightfold
symmetry is restored. In this regime, a secondary ring of dominant momentum peaks appears at smaller wave vectors, indicating longer-wavelength density modulations and a crossover from
lattice-dominated to interaction-driven quasicrystalline order. In contrast, imbalanced mixtures form partially miscible density clusters with eightfold-symmetric aperiodic patterns only at intermediate coupling, while stronger interactions drive global phase separation and permanently destroy quasicrystalline order. Real-time simulations demonstrate that these aperiodic structures are dynamically stable and experimentally accessible. Our results show that quasicrystalline order can emerge in binary condensates without explicitly aperiodic
lattices and reveal population balance as a key ingredient for stabilizing
quantum quasicrystals.
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All authors Abid Ali, Pei Zhang, Hiroki Saito, Yong-Chang Zhang
Materials Science · Cross-listed from physics.optics
Hybrid Femtosecond Laser and Ion-Implantation Processing for Controlled, Deep, High-Efficiency Ablation in Fused Silica
Mario Garcia-Lechuga, Yoann Levy, Irene Solana et al. (+3 more)
Femtosecond
laser modification of fused silica enables precise surface tailoring for the fabrication of micro-optical components such as microlenses and diffractive elements. However, the process is governed by
laser-matter interactions where the local fluence determines the processing depth, often limiting control over feature geometry and efficiency. Here, we present a hybrid approach combining localized Au implantation (1.8 MeV Au2+ ions) into SiO2 samples with femtosecond
laser irradiation (250 fs), effectively tuning the
laser-matter interaction and resulting morphology. At both 515 nm and 1030 nm irradiation wavelengths, single-shot femtosecond pulses produce cylindrical craters with sharp edges and flat-bottom profiles. Independently of the fluence, these craters exhibit a constant depth of 550 nm, corresponding to the region of maximum Au concentration. The effect manifests already at moderate fluence (app. 4 J/sq.cm) and yields high ablation efficiency, up to 15 cubic micrometers per microjoule. The hybrid method also works effectively at lower implantation doses that preserve the excellent transmission of fused silica, offering a promising pathway for the high-quality fabrication of flat optical components such as binary phase masks, phase lenses, or fused-silica micromolds.
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All authors Mario Garcia-Lechuga, Yoann Levy, Irene Solana, Fatima Cabello, Maria Dolores Ynsa, Nadezhda M. Bulgakova
Statistical Mechanics · Cross-listed from hep-th
Deconfinement from Thermal Tensor Networks: Universal CFT signature in (2+1)-dimensional $\mathbb{Z}_N$ lattice gauge theory
Adwait Naravane, Yuto Sugimoto, Shinichiro Akiyama et al. (+2 more)
Tensor networks offer a sign-problem-free approach to study
lattice gauge theories, but extracting precise universal information associated with the deconfinement transition remains challenging. In this work, we study the deconfinement transition of (2+1)-dimensional $\mathbb{Z}_N$
lattice gauge theories at finite temperature using a thermal tensor network approach, where the partition functions at finite temperature are formulated as three-dimensional tensor networks. These tensor networks are first contracted in the temporal direction, and the subsequent coarse-graining in the spatial directions yields a renormalized transfer
matrix, the spectrum of which directly encodes the universal conformal field theory data. In particular, by numerically extracting the central charge and scaling dimensions, we verify that the universality class of the thermal deconfinement transition matches the prediction of the Svetitsky-Yaffe
conjecture for $N=2,3,5$. Moreover, we show that the $\mathbb{Z}_5$ theory at finite temperature exhibits an intermediate phase with an emergent U(1)
symmetry. Critical couplings are determined via Gu-Wen ratios and agree with existing Monte Carlo simulations. Finally, extrapolating these critical couplings at finite temperature enables us to determine the deconfinement transition points for $N=2,3$ at zero temperature.
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All authors Adwait Naravane, Yuto Sugimoto, Shinichiro Akiyama, Jutho Haegeman, Atsushi Ueda
Other Condensed Matter
Enhanced Spin Lifetime and Long-Range Spin Transport in p-Silicon using Spin Gapless Semiconductor as Ferromagnetic Injector
Nilay Maji, Subham Mohanty, Pujarani Dehuri et al. (+1 more)
Electrical
spin injection and transport in silicon are central challenges for realizing
semiconductor-based spintronic devices, particularly in p-type Si, where strong
spin relaxation and interface effects often suppress detectable
spin signals. Here, we report electrical
spin injection, accumulation, and transport in lightly doped p-type silicon using the
spin-gapless Heusler compound Mn$_2$CoAl as a
ferromagnetic spin injector, separated from the p-Si channel by a thin MgO tunnel barrier in a lateral device geometry.
Spin transport is systematically investigated through three-terminal (3-T) Hanle and four-terminal (4-T) nonlocal (NL)
spin-valve and Hanle measurements. Clear Lorentzian Hanle signals are observed in the 3-T configuration from 5 K up to room temperature, yielding a
spin lifetime of $\sim$0.68 ns at 300 K that increases to $\sim$4.11 ns at 5 K. Temperature-dependent analysis reveals a weak power-law dependence of the
spin lifetime, indicating Bir–Aronov–Pikus–type
spin relaxation mechanism. To validate genuine
spin transport, NL
spin-valve and Hanle measurements were performed, revealing well-defined
spin-valve switching and controlled
spin precession at 5 K. From NL Hanle fitting, a
spin lifetime of $\sim$5.65 ns and a
spin diffusion length of $\sim$0.82 $\mu$m are extracted, confirming diffusive long-range
spin transport in the p-Si channel. Although NL signals diminish at elevated temperatures due to reduced interfacial
spin polarization and thermal noise, the combined 3-T and 4-T results establish
spin-gapless Mn$_2$CoAl as an effective
spin injector for p-type silicon. These findings highlight the potential of
spin-gapless
semiconductors for improving
spin injection efficiency and advancing Si-compatible spintronic devices.
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All authors Nilay Maji, Subham Mohanty, Pujarani Dehuri, Garima Yadav
Materials Science
Valence-free open nanoparticle superlattices
Binay P. Nayak, Zinnia Mallick, Wenjie Wang et al. (+7 more)
A cornerstone of advanced materials design is establishing a framework for assembling nanoparticle superstructures with tailored
symmetries. A longstanding challenge has been assembling diamond-like superstructures for photonic devices. Traditionally, such open superstructures require functionalized nanoparticles with directional or anisotropic interactions, reminiscent of valence bonding in a diamond. Here, we present a robust strategy for assembling valence-free nanoparticles into a broad array of cubic superstructures. By grafting nanoparticles with oppositely charged, end-functionalized water-soluble
polymers of adjustable molecular weight, we gain control over electrostatic interactions and conformational constraints. This unified approach yields
lattices analogous to rock salt, CsCl, zinc-blende, diamond, and the rare simple cubic phase, with tunable
lattice constants. Theoretical models and simulations elucidate the underlying interactions, providing a framework for engineering valence-free nanoparticle superlattices.
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All authors Binay P. Nayak, Zinnia Mallick, Wenjie Wang, Prapti Kakkar, Shan Zhou, Honghu Zhang, Dmytro Nykypanchuk, Surya K. Mallapragada, Alex Travesset, David Vaknin
Materials Science
Unveiling the origin of the capacity fade in MnO$_{2}$ zinc-ion battery cathodes through an analysis of the Mn vacancy formation
Caio M. Miliante, Kevin J. Sanders, Liam J. McGoldrick et al. (+5 more)
Currently explored rechargeable aqueous zinc-ion battery (RAZIB) cathode materials, such as $\alpha$-MnO$_{2}$, suffer from severe capacity fade when cycling at rates appropriate for grid-scale operation. Mn dissolution has been previously identified as the cause of $\alpha$-MnO$_{2}$ cathode degradation during RAZIB cycling, with conflicting evidence being found in support of the proposed Jahn-Teller effect-assisted charge disproportionation reaction as the mechanism behind Mn dissolution. In order to unveil the Mn dissolution mechanism in MnO$_{2}$ cathode
cells under RAZIB operation conditions, the energetic feasibility for Mn vacancy formation was probed in both charged (MnO$_{2}$) and discharged (ZnMn$_{2}$O$_{4}$) phases of $\alpha$ and $\lambda$ polymorphs of MnO$_{2}$ using density functional theory. The formation of a Mn vacancy, and consequently the dissolution of Mn as Mn$^{2+}_{(aq)}$, was found to be thermodynamically feasible for the $\alpha$-ZnMn$_{2}$O$_{4}$ phase due to the energetically unfavourable Zn bent coordination formed during the Zn$^{2+}$ intercalation process, indicating that Mn dissolution is promoted by an unstable Zn coordination environment. The theoretical calculations were then corroborated by operando $^{1}$H
nuclear magnetic resonance experiments which captured the Mn dissolution occurring throughout the RAZIB discharge, with subsequent electrochemical deposition of the Mn atoms on the electrode during charge. The combined computational and experimental analysis reveals the critical role of defect energetics and coordination environment in driving active material dissolution, and consequently capacity fade, with the proposed mechanism also relevant for understanding cathode degradation in other intercalating ion battery chemistries.
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All authors Caio M. Miliante, Kevin J. Sanders, Liam J. McGoldrick, Nicola Seriani, Brian D. Adams, Gillian R. Goward, Drew Higgins, Oleg Rubel
Strongly Correlated Electrons
Hierarchical quasiparticle dynamics in antiferromagnets revealed by time- and momentum-resolved X-ray scattering
Arnau Romaguera, Elizabeth Skoropata, Yun Yen et al. (+18 more)
Energy flows among coupled subsystems are essential for ultrafast dynamics and high-speed technologies. In
magnetic materials,
spin fluctuations –
magnons – mediate these flows in ultrafast magnetism. Yet momentum-resolved access to low-energy
magnons governing the microscopic dynamics has been lacking. Using time-resolved resonant diffuse scattering alongside complementary time-resolved X-ray techniques and
quantum-kinetic simulations, we unveil the hierarchical energy pathways among correlated systems in the photoexcited antiferromagnet CuO. Above-bandgap excitation triggers near-instantaneous
spin disorder, generating non-thermal
magnons throughout reciprocal space within femtoseconds. Real-time momentum-resolved tracking reveals picosecond
magnon quasi-thermalization, followed by nanosecond recovery via momentum-selective
magnon-
phonon scattering. The quasiparticle dispersion mismatch creates recovery bottlenecks that control non-
equilibrium lifetimes. This microscopic framework transcends phenomenological models and generalizes across materials, establishing design principles for ultrafast control of material properties.
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All authors Arnau Romaguera, Elizabeth Skoropata, Yun Yen, Biaolong Liu, Abhishek Nag, Shih-Wen Huang, Ludmila Leroy, Katja Sophia Moos, Gian Parusa, Serhane Zerdane, Ritwika Mandal, Celine Mariette, Matteo Levantino, Eugenio Paris, Luc Patthey, Ekaterina Pomjakushina, Urs Staub, Monica Ciomaga Hatnean, Michael Schueler, Elia Razzoli, Hiroki Ueda
Materials Science
Physics-Informed Glass-Structure Descriptors for Assessing the Intrinsic Reactivity of Mixed Amorphous-Crystalline Precursors in Alkali-Activated Materials
Zhu Pan, Xinru Li, Yucheng Wang et al. (+2 more)
Rapid and reliable assessment of the intrinsic reactivity of amorphous aluminosilicates is critical for their application in alkali-activated materials (AAMs) and blended cements. Although physics-informed glass-structure descriptors have demonstrated strong structure-reactivity relationships for predominantly amorphous systems, their extension to heterogeneous precursors with mixed crystalline-amorphous phases has been limited. Here, quantitative X-ray diffraction combined with bulk compositional analysis was used to reconstruct the effective amorphous compositions of five fly ashes (FAs) and three ground granulated blast-furnace slags (GGBSs). These compositions served as inputs for molecular dynamics simulations employing a melt-and-quench approach to generate atomic-scale structural models of the glassy phases. Based on these structures, the previously introduced descriptors, i.e., average metal oxygen dissociation energy and average metal oxygen bond strength, were refined to cover a broader compositional space spanning SiO2-Al2O3-TiO2-Fe2O3-CaO-MgO-MnO-Na2O-K2O. The refined descriptors exhibit strong inverse correlations with multiple independent reactivity indicators, including cumulative heat release from isothermal calorimetry, bound water content from thermogravimetric analysis, and compressive strength, for both single precursors and binary FA-GGBS blends activated with NaOH. These results demonstrate that physics-informed glass-structure descriptors can be extended from ideal amorphous systems to heterogeneous mixed-phase precursors and capture relative intrinsic reactivity trends in alkaline solutions. The proposed framework provides a transferable, structure-informed basis for comparative assessment of precursor reactivity that complements experimental testing and may inform precursor screening and mix designs for AAM and blended cement systems.
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All authors Zhu Pan, Xinru Li, Yucheng Wang, Samira Hossain, Kai Gong
Statistical Mechanics · Cross-listed from quant-ph
Theory of Steady States for Lindblad Equations beyond Time-Independence: Classification, Uniqueness and Symmetry
Hironobu Yoshida and Ryusuke Hamazaki
We present a rigorous and comprehensive classification of the asymptotic behavior of time-dependent Gorini-Kossakowski-Sudarshan-Lindblad (GKSL) equations under the assumption of Hermitian jump operators. Our results apply to a broad class of GKSL equations whose time dependence is assumed to be recurrent, including time-independent, periodic, quasiperiodic, and certain classes of random time dependence. Our main contributions are twofold: first, we establish a criterion for the uniqueness of steady states. The criterion is formulated in terms of the
algebra generated by the GKSL generators and provides a necessary and sufficient condition when the generators are analytic functions of time. We demonstrate the utility of our criterion through prototypical examples, including
quantum many-body
spin chains. Second, we extend the concept of strong
symmetry for time-dependent GKSL equations by introducing two distinct forms, strong
symmetry in the Schrödinger picture and that in the interaction picture, and completely classify the asymptotic dynamics with them. More concretely, we rigorously uncover that the strong
symmetry in the interaction picture is responsible for non-trivial time-dependent steady states, such as coherent oscillations, whereas that in the Schrödinger picture controls the existence of time-independent steady states. This classification not only encompasses established mechanisms underlying non-trivial oscillatory steady states, such as strong dynamical
symmetry and Floquet dynamical
symmetry, but also reveals
symmetry-predicted, time-dependent asymptotic dynamics in a novel class of open
quantum systems. Our framework thus provides a rigorous foundation for controlling dissipative
quantum systems in a time-dependent manner.
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