Quantum Gases · Cross-listed from physics.optics
Mechanisms of localization in a finite harmonically confined optical superlattice
A. Katsaris, I. A. Englezos, C. Weitenberg et al. (+2 more)
We investigate the impact of harmonic confinement in a finite optical superlattice and reveal the different mechanisms that can lead to the emergence of localized states. The optical superlattice, with odd or even number of unit
cells, can exhibit either a trivial or a non-trivial underlying
topology, characterized by the corresponding Zak phase. We focus on a distinct localization mechanism in the intermediate harmonic trapping frequency regime. Specifically, the four lowest-lying eigenstates in this regime form an effective four-level system in the topologically non-trivial configuration. Larger trapping frequency values drive the system into a harmonic trap dominated regime, featuring classical pairing and localization of all states of the lower band, as in a usual optical
lattice. For the lower trapping frequency regime, the fate of topological edge states is discussed. Our results are based on exact diagonalization and on a tight-binding approximation that maps the continuous to a discrete system. We address several aspects relevant to the experimental implementation of optical superlattices and provide a brief illustration of the dynamics, highlighting direct ways to observe and distinguish between the different localization mechanisms.
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All authors A. Katsaris, I. A. Englezos, C. Weitenberg, F. K. Diakonos, P. Schmelcher
Materials Science
Revealing the interfacial kinetic mechanisms in high-entropy doped Na$_3$V$_2$(PO$_4$)$_3$ through electrochemical investigation and distribution of relaxation times
Manish Kr. Singh and Rajendra S. Dhaka
We designed a high-
entropy doped NASICON cathode, Na$_3$V$_{1.9}$(CrMoAlZrNi)$_{0.1}$(PO$_4$)$_3$ and investigate its electrochemical performance for sodium-ion batteries (SIBs) to understand the
diffusion mechanism including distribution of relaxation times analysis of interfacial kinetics. This trace doping induces high-
entropy mixing at the vanadium site, tuning the
lattice and enhancing specific capacity, activating V$^{4+}$/V$^{5+}$ redox couple 3.95~V. Interestingly, it delivers a reversible capacity of 119~mAh~g$^{-1}$ at 0.1~C, and demonstrate excellent stability of 68% after 1000 cycles at 10~C. The calculated
diffusion coefficient values are found within the range of \(10^{-11}\)–\(10^{-13}~\mathrm{cm^2\,s^{-1}}\). The systematic investigation of temperature and voltage-dependent impedance data using the distribution of relaxation times provides deeper insights into the underlying charge-transfer and transport processes. The full
cells with hard carbon delivers 326~Wh~kg$^{-1}$ (with respect to cathode mass) at $\approx$3.2~V and retained $\sim$79% capacity after 100 cycles at 2~C. Our study opens new avenues for developing high-
entropy doped cathodes for enhanced structural stability, extended redox activity, and optimized electrochemical kinetics for practical implementation of SIBs.
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Statistical Mechanics
Probabilities of rare events in product kernel aggregation: An exact formula and phase diagram
R. Goutham, R. Rajesh, V. Subashri et al. (+1 more)
We present an exact method for calculating the large deviation function describing rare fluctuations in the number of particles for product-kernel aggregation. Starting from the master equation, we derive an exact integral representation for the probability $P(M,N,t)$ of observing $N$ particles at time $t$ starting from $M$ monomers for any finite $M, N, t$. From this, we obtain an exact expression for the exponential moment $\langle p^N\rangle$ for integer $p$. Employing a replica
conjecture – numerically validated by finite-$M$ scaling – we extend this result to real $p \geq 0$. The convex envelope of the large deviation function, obtained via a Legendre-Fenchel transform of the exponential moment, shows singular behavior. The singular structure allows us to construct the full phase diagram of product-kernel aggregation, which contains a tricritical point, separating continuous and discontinuous transitions. We also compute the asymptotic form of the LDF for small $N/M$.
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All authors R. Goutham, R. Rajesh, V. Subashri, Oleg Zaboronski
Materials Science
Flexocurrent-induced magnetization: Strain gradient-induced magnetization in time-reversal symmetric systems
Shinnosuke Koyama, Takashi Koretsune and Kazumasa Hattori
Symmetry constraints determine which physical responses are allowed in a given system. Magnetization induced by strain fields, such as in piezomagnetic and flexomagnetic effects, has typically been considered in materials that break time-reversal
symmetry. Here, we propose that nonuniform strain can induce magnetization even in nonmagnetic metals and
semiconductors that preserve time-reversal
symmetry. This mechanism differs from the conventional flexomagnetic effect: the strain gradient acts as a driving force on the electrons, generating magnetization in a manner closely analogous to current-induced magnetization. Treating the strain field as an external field, we derive a general expression for the magnetization induced by a strain gradient and demonstrate that this response is
symmetry-allowed even in time-reversal symmetric systems. We apply our formulation to nonmagnetic systems that lack spatial inversion
symmetry while preserving time-reversal
symmetry, using a decorated square
lattice, monolayer MoS$_2$, and monolayer Janus MoSSe as representative examples. We find a finite magnetization response to strain gradients, which is consistent with
symmetry arguments, supporting the validity of our theoretical framework. These results offer a pathway for controlling magnetization in nonmagnetic materials using strain fields.
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Statistical Mechanics
Population dynamics simulations of large deviations for three subclasses of the Kardar-Parisi-Zhang universality class
Yuta Yanagibashi and Kazumasa A. Takeuchi
Recent theoretical studies have gradually deepened our understanding of the one-dimensional (1D) Kardar-Parisi-Zhang (KPZ) universality class even in the large deviation regime, but numerical methods for studying KPZ large deviations remain limited. Here we implement a method based on the population dynamics
algorithm for studying large deviations of time-integrated local currents in the totally asymmetric simple exclusion process (TASEP), which is a pragmatic model in the 1D KPZ class. Carrying out simulations for the three representative initial conditions, namely step, flat, and stationary ones, we not only confirm theoretical predictions available for the step case, but also characterize large deviations for the flat and stationary cases which have not been investigated before. We reveal in particular an unexpected robustness of the deeply negative large deviation regime with respect to different initial conditions. We attribute this robustness to the spontaneous formation of a wedge shape in interface profile. Our population dynamics approach may serve as a versatile method for studying large deviations in the KPZ class numerically and, potentially, even experimentally.
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Statistical Mechanics
Area under subdiffusive random walks
Vicenç Méndez, Rosa Flaquer-Galmés and Javier Cristín
We study the statistical properties of the area and the absolute area under the trajectories of subdiffusive random walks. Using different frameworks to describe subdiffusion (as the scaled Brownian motion, fractional Brownian motion, the continuous-time random walk or the Brownian motion in heterogeneous media), we compute the first two moments, the ergodicity breaking parameter for the absolute area and infer a general scaling for the probability density functions of these functionals. We discuss the differences between the statistical properties of the area and the absolute area for the different subdiffusion models and illustrate the experimental interest of our results. Our theoretical findings are supported by Monte Carlo simulations showing an excellent agreement.
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Materials Science
Dynamics of Long-lived Carriers in Molybdenum Carbide Nanosheets
Xiangyu Zhu, Zhong Wang, Tao Li et al. (+5 more)
Molybdenum carbide (MoC) is a promising candidate for substituting expensive platinum-group metals in many applications owing to its low cost and excellent properties, therefore a comprehensive understanding of its carrier dynamics is demanded for advancing the synthesis strategy and implementation of MoC. In this work, the carrier relaxation in MoC nanosheets is investigated by combining the femtosecond transient reflection spectroscopy with the first-principles calculations. The measured processes of electron-electron, electron-
phonon, and
phonon-
phonon scattering show significantly longer lifetimes compared to those of other transition metal carbides. Through the analysis of calculated
phonon dispersion, the nanosecond carrier lifetime is explained by the restricted
phonon decay pathways, which is induced by the large mass difference between Mo and C atoms. The observed slow carrier cooling rate in our study offers a straightforward approach for effectively utilizing hot carriers, which is expected to improve the performance of photothermal and photovoltaic devices.
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All authors Xiangyu Zhu, Zhong Wang, Tao Li, Xi Wang, Zheng Zhang, Chunlong Hu, Kaifu Huo, Wenxi Liang
Mesoscale and Nanoscale Physics
Coherent electronic Raman excitation of valley-orbit split states of phosphorus dopants in silicon
Adam Gindl, Martin Čmel, František Trojánek et al. (+4 more)
In this study, we demonstrate coherent optical excitation of the electronic Raman transition between the $1s\left(A_1\right)$ and $1s\left(E\right)$ split states of phosphorus donor in crystalline silicon. The dynamics of the generated wavepacket is characterized in the time domain using a degenerate pump-probe technique with mid-infrared femtosecond pulses via transient polarization anisotropy of the probe pulse. In addition, we study the role of resonantly excited carriers, and we show that the amplitude and coherence time of the electronic wavepacket depend on the pre-excited carrier density. Further, we demonstrate that under certain conditions, the Raman-type excitation changes to displacive impulsive excitation, which allows us to address the Raman-forbidden transition between $1s\left(A_1\right)$ and $1s\left(T_1\right)$.
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All authors Adam Gindl, Martin Čmel, František Trojánek, Petr Malý, Zbyněk Šobáň, Alexandr Pošta, Martin Kozák
Statistical Mechanics
Critical behavior of isotropic systems with strong dipole-dipole interaction from the functional renormalization group
Georgii Kalagov and Nikita Lebedev
We compute the critical exponents of three-dimensional magnets with strong dipole-dipole interactions using the functional renormalization group (FRG) within the local potential approximation including the wave function renormalization (LPA$^\prime$). The system is governed by the Aharony fixed point, which is scale-invariant but lacks conformal invariance. Our nonperturbative FRG analysis identifies this fixed point and determines its scaling behavior. The resulting critical exponents are found to be close to those of the Heisenberg $O(3)$ universality class, as computed within the same FRG/LPA$^\prime$ framework. This proximity confirms the distinct yet numerically similar nature of the two universality classes.
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Statistical Mechanics
Statistical Mechanics of the Sub-Optimal Transport
Riccardo Piombo, Lorenzo Buffa, Dario Mazzilli et al. (+1 more)
Statistical mechanics is a powerful framework for analyzing optimization yielding analytical results for matching, optimal transport, and other combinatorial problems. However, these methods typically target the zero-temperature limit, where systems collapse onto optimal configurations, a.k.a. the ground states. Real-world systems often occupy intermediate regimes where
entropy and cost minimization genuinely compete, producing configurations that are structured yet sub-optimal. The Sub-Optimal Transport (SOT) model captures this competition through an ensemble of weighted bipartite graphs: a coupling parameter interpolates between
entropy-dominated dense configurations and cost-dominated sparse structures. This crossover has been observed numerically but lacked analytical understanding. Here we develop a mean-field theory that characterizes this transition. We show that local fluctuations in Lagrange multipliers become sub-extensive in the thermodynamic limit, reducing the full model with strength constraints to an effective single-constraint problem admitting an exact solution in some intermediate regime. The resulting free energy is analytic in the coupling parameter, confirming a smooth crossover rather than a phase transition. We derive closed-form expressions for thermodynamic observables and weight distributions, validated against numerical simulations. These results establish the first analytical description of the SOT model, extending statistical mechanics methods beyond the zero-temperature regime.
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All authors Riccardo Piombo, Lorenzo Buffa, Dario Mazzilli, Aurelio Patelli
Mesoscale and Nanoscale Physics
Controlling Spin-Mixing Conductance in KTaO$_{3}$ 2DEGs by Varying Argon-Ion Irradiation Time
Yasar K. Arafath, Vaishali Yadav, Nidhi Kandwal et al. (+3 more)
The Rashba-split two-dimensional electron gas (2DEG) at the surface and interface of insulating
oxides like KTaO$_{3}$ (KTO) shows great promise for all-
oxide spintronics. However, efficient
spin current injection into the adjacent 2DEG remains a key challenge. In this study, we report the
spin-pumping experiments on a 2DEG formed on the (001)KTO surface via Ar$^+$ irradiation. We observed a significant increase in
magnetic damping in the Ar$^+$-KTO/Py
bilayer compared to a non-irradiated KTO/Py control sample, confirming
spin pumping into the 2DEG. We demonstrate that the
spin-mixing conductance ($g_{\uparrow\downarrow}^r$) can be substantially enhanced by controlling the Ar$^+$ irradiation time. The enhancement is attributed to increased 2DEG conductance, which results from a higher concentration of oxygen vacancies with longer irradiation times. This work provides crucial guidance for optimizing
spin-to-charge conversion in KTO-based systems, highlighting the potential of Ar$^+$-irradiated KTO 2DEGs for future
oxide spintronics.
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All authors Yasar K. Arafath, Vaishali Yadav, Nidhi Kandwal, P.N. Santhosh, Pranaba Kishore Muduli, Prasanta Kumar Muduli
Materials Science
High-Throughput Discovery of Two-Dimensional Materials Exhibiting Strong Rashba-Edelstein effect
Binchang Zhou, Baoru Pan, Pan Zhou et al. (+3 more)
The Rashba-Edelstein effect (REE), which generates
spin accumulation under an applied electric current, quantifies charge-to-
spin conversion (CSC) efficiency in non-centrosymmetric systems. However, systematic investigations of REE in two-dimensional (2D) materials remain scarce. To address this gap, we perform a comprehensive
symmetry analysis based on the 80 crystallographic layer groups, elucidating the relationship between materials'
symmetries and the
geometric characteristics of the REE response tensor. Our analysis identifies 13 distinct
symmetry classes for the tensor and reveals all potential material candidates. Considering the requirement of strong
spin-orbit coupling for a large REE response, we screen the C2DB database and identify 54 promising 2D materials. First-principles calculations demonstrate that the largest REE response coefficients in these materials exceed those reported for other 2D systems by an order of magnitude, indicating exceptionally high CSC efficiency. Focusing on three representative materials, including HgI2, AgTlP2Se6 and BrGaTe, we show that their large response coefficients can be well explained by effective kp models and the characteristic
spin textures around high-
symmetry points in momentum space. This work provides a systematic framework and identifies high-performance candidates, paving the way for future exploration of REE-driven CSC in 2D materials.
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All authors Binchang Zhou, Baoru Pan, Pan Zhou, Yuzhong Hu, Songmin Liu, Lizhong Sun
Materials Science
Robust, High-Contrast, Recyclable Zinc-Based Dynamic Windows via Synergistic Electrolyte and Interfacial Engineering
Fei Peng, Zhichao Liang, Zhoutao Yang et al. (+3 more)
Zinc-based electrochromic devices offer a sustainable route for dynamic optical management but are plagued by poor cycling stability due to irreversible zinc plating/stripping and side reactions. Herein, we report a robust, high-contrast, and recyclable zinc-based dynamic window enabled by a synergistic electrolyte and interfacial engineering strategy. Molecular dynamics simulations and electrochemical analyses reveal a dual-ion cooperative mechanism that governs the reversibility: anions with the strongest binding affinity guide uniform Zn deposition by stabilizing the inner solvation shell, while formate anions co-enriched at the interface facilitate smooth stripping via protonation during the oxidation process. This orchestrated interplay effectively eliminates "dead Zn" accumulation and dendrite growth. Consequently, the device demonstrates a record-high lifespan of 15,000 cycles with negligible degradation and maintains a large optical modulation of >50%, along with multiple optical states (transparent, gray, black, and mirror). Furthermore, it achieves a large reflectance modulation (>50%) stable for over 2,000 cycles. This work establishes the recyclable zinc-based dynamic window as a scalable, high-performance alternative to conventional electrochromic systems, advancing the feasibility of solution-processed energy-saving windows in sustainable buildings.
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All authors Fei Peng, Zhichao Liang, Zhoutao Yang, Yijia Chen, Wenjie Mai, Chuanxi Zhao
Mesoscale and Nanoscale Physics
Piezomagnetic transport in van der Waals noncoplanar Antiferromagnets
Abdul Ahad, Miuko Tanaka, Nguyen Duy Khanh et al. (+7 more)
The piezomagnetic effect-strain-induced linear modulation of magnetization, arises in magnets with broken time-reversal
symmetry (BTRS), offering a pathway to bidirectional strain-based control of magnetism, which is an essential straintronic and spintronic functionality in solids. Metallic antiferromagnets with BTRS provide an ideal platform to study this effect through transport measurements, yet experimental demonstrations are limited. Van der Waals (vdW) nanomagnets, with their mechanical flexibility, are particularly promising for realizing large piezomagnetic responses and effective transport control. Here we demonstrate piezomagnetic control of electronic transport in nano-devices of the vdW antiferromagnets CoNb$_3$S$_6$ and CoTa$_3$S$_6$, archetypal vdW metals with BTRS that exhibit a spontaneous
Hall effect. Applying uniaxial strain linearly modulates both the
antiferromagnetic transition temperature and coercive field, consistent with strain-driven tuning of exchange coupling, key signatures of the piezomagnetic effect. Moreover, spontaneous
Hall effect is controllable via strain, evidencing piezomagnetic tuning of Berry
curvature and its associated
geometric transport. These findings establish piezomagnetism as a powerful route to manipulate
antiferromagnetic transport, opening avenues for straintronic and spintronic applications in vdW
magnetic systems.
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All authors Abdul Ahad, Miuko Tanaka, Nguyen Duy Khanh, Riku Ishioka, Aki Kitaori, Tenta Kitamura, Hao Ou, Jiang Pu, Shinichiro Seki, Toshiya Ideue
Strongly Correlated Electrons · Cross-listed from hep-th
Boundary conformal field theory, holography and bulk locality
Pinaki Banerjee, Parijat Dey and Dipyendu Dhar
We study bulk locality in a scalar effective field theory (EFT) in AdS background in presence of an end-of-the-world (EOW) brane. The
holographic dual description is given in terms of a boundary conformal field theory (BCFT). We compute the two point correlation function of scalar operators in the BCFT using the one-loop Witten diagrams and compare its analytic structure with the constraints imposed by boundary conformal
symmetry. We find that the loop-corrected correlator derived from a local bulk description is not fully compatible with BCFT expectations. This result places nontrivial constraint on bulk locality in
holographic BCFT constructions and identifies BCFT correlators as sensitive probes of
quantum bulk dynamics in presence of boundaries.
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Statistical Mechanics
Restoring Sparsity in Potts Machines via Mean-Field Constraints
Kevin Callahan-Coray, Kyle Lee, Kyle Jiang et al. (+1 more)
Ising machines and related probabilistic hardware have emerged as promising platforms for NP-hard optimization and sampling. However, many practical problems involve constraints that induce dense or all-to-all couplings, undermining scalability and hardware efficiency. We address this constraint-induced density through two complementary approaches. First, we introduce a hardware-aware native formulation for multi-state probabilistic digits (p-dits) that avoids the locally dense intra-variable couplings required by binary Ising encodings. We validate p-dit dynamics by reproducing known critical behavior of the 2D Potts model. Second, we propose mean-field constraints (MFC), a hybrid scheme that replaces dense pairwise constraint couplings with dynamically updated single-node biases. Applied to balanced graph partitioning, MFC achieves solution quality comparable to exact all-to-all constraint formulations while dramatically reducing graph density. Finally, we demonstrate the practical impact of restored sparsity through an FPGA implementation. In comparisons using FPGA kernel time and CPU solver-loop time, and excluding the current prototype's host-device schedule transfer overhead, the FPGA reaches the 50% success threshold more than an order of magnitude faster than the CPU probabilistic solvers and more than two orders of magnitude faster than the Tabu Ising baseline. Together, these results outline a pathway for scaling constrained optimization on probabilistic hardware.
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All authors Kevin Callahan-Coray, Kyle Lee, Kyle Jiang, Kerem Y. Camsari
Mesoscale and Nanoscale Physics
Universal Quantized Berry-Dipole Flat Bands
Qingyang Mo and Shuang Zhang
Perfectly flat bands with nontrivial
quantum geometry have emerged as a frontier for exotic topological phenomena and
superconductors. Here, we unveil a universal family of quantized Berry-dipole flat bands in
chiral-symmetric (2n+1)-band systems, where the central perfectly flat band carries a Berry-dipole moment d=n, with n an arbitrary integer, while preserving zero Chern number. We construct explicit
lattice models to showcase three topological phenomena characterized by the Berry-dipole moment: a flat-band returning pump featuring bidirectional,
soliton-like displacement of Wannier centers by exactly n unit
cells per half cycle, a dipolar Haldane phase diagram arising from the competition between time-reversal and parity
symmetries, and n pairs of bulk helical zero modes whose existence depends on the orientation of pseudomagnetic field. Our findings establish a universal framework for the
topology beyond Chern class in perfectly flat bands and provide a tunable platform for exploring
quantum geometry and interaction-driven phases.
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Materials Science
Long-range orbital transport and inverse orbital Hall effect in Co/Ru-based terahertz emitters
Zhou Chao, Zhang Shaohua, Hao Lei et al. (+10 more)
The utilization of terahertz (THz) emission spectroscopy in femtosecond photoexcited spintronic
heterostructures has emerged as a versatile tool for investigating ultrafast
spin-transport in a noncontact and non-invasive manner. However, the investigation of ultrafast orbital-transport is still in the primitive stage. Here, we experimentally demonstrate the orbital-to-charge current conversion in Co/Ru
heterostructures. Time-domain measurements reveal delayed and broadened terahertz waveforms with increasing Ru thickness, consistent with long-range orbital transport. In Co/Pt/Ru trilayers, the terahertz emission is further enhanced through constructive interference between the inverse
spin Hall effect (ISHE) in Pt and inverse orbital
Hall effect (IOHE) in Ru, while reversed stack structures show suppressed output.
Ferromagnetic resonance (FMR) measurements reveal a strong correlation between damping and THz amplitude, highlighting efficient angular momentum conversion. These results position Co/Ru as a promising orbitronic platform for tunable ultrafast THz emission. Our results not only strengthen the physical mechanism of condensed matter physics but also pave the way for designing promising
spin-orbitronic devices and terahertz emitters.
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All authors Zhou Chao, Zhang Shaohua, Hao Lei, Jin Yaxuan, Jiang Xianguo, Yang Ning, Zheng Li, Meng Hao, Lu Chao, Huang Wendeng, Wu Yizheng, Zhou Yan, Jia Xu
Mesoscale and Nanoscale Physics
Observation of Orbit-Orbit Torques: Highly Efficient Torques on Orbital Moments Induced by Orbital Currents
Hongyu Chen, Han Yan, Xiaorong Zhou et al. (+10 more)
We study the current-induced torques in
bilayers composed of a light 3d metal, chromium, and a rare-earth ferromagnet with finite orbital moments, terbium, utilizing second-harmonic
Hall-response measurements. The dampinglike torque efficiency of chromium is found to be positive and reaches ~3.66 in this system, in sharp contrast to the negative and subtle dampinglike torque efficiency in general Cr/ferromagnet
heterostructures with quenched orbital moment. We suggest that the orbital currents generated by the orbital
Hall effect in Cr can be injected into Tb with negligible loss at the interface and then efficiently interact with the orbital moments. We term such an exotic effect as the orbit-orbit torque (OOT). Our work implies that orbital currents could be harnessed to manipulate the orbital magnetization of materials, which would advance the development of orbitronics.
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All authors Hongyu Chen, Han Yan, Xiaorong Zhou, Xiaoning Wang, Ziang Meng, Li Liu, Guojian Zhao, Zhiyuan Duan, Sixu Jiang, Jingyu Li, Xiaoyang Tan, Peixin Qin, Zhiqi Liu
Disordered Systems and Neural Networks · Cross-listed from q-bio.PE
A brief review of evolutionary game dynamics in the reinforcement learning paradigm
Guozhong Zheng, Xin Ou, Shengfeng Deng et al. (+2 more)
Cooperation,
fairness, trust, and resource coordination are cornerstones of modern civilization, yet their emergence remains inadequately explained by the persistent discrepancies between theoretical predictions and behavioral experiments. Part of this gap may arise from the imitation learning paradigm commonly used in prior theoretical models, which assumes individuals merely copy successful neighbors according to predetermined, fixed rules. This review examines recent advances in evolutionary game dynamics that employ reinforcement learning (RL) as an alternative paradigm. In RL, individuals learn through trial and error and introspectively refine their strategies based on environmental feedback. We begin by introducing key concepts in evolutionary game theory and the two learning paradigms, then synthesize progress in applying RL to elucidate cooperation, trust,
fairness, optimal resource coordination, and ecological dynamics. Collectively, these studies indicate that RL offers a promising unified framework for understanding the diverse social and ecological phenomena observed in human and natural systems.
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All authors Guozhong Zheng, Xin Ou, Shengfeng Deng, Jiqiang Zhang, Li Chen
Quantum Gases
Dynamics of string breaking and revival in a Rydberg atomic chain
Xin Liu, Han-Chao Chen, Zheng-Yuan Zhang et al. (+8 more)
String breaking is one of the most representative non-perturbative dynamics processes in confinement theory, typically associated with the creation of particle-antiparticle pairs. In this paper, we take a one-dimensional Rydberg atomic chain to theoretically study the dynamical of finite-length string state. Under different string tension conditions, we find that the string dynamics exhibits two clearly distinguishable
evolution characteristics: one is that the string breaks and the system enters a superposition state space containing multiple
meson state configurations; the other is localized string dynamics, in which the string undergoes local breaking but can then recombine and return to a state close to the initial structure, with the breaking and recombination processes recurring over a long time scale. Through the analysis of the
evolution of different
meson state configurations, we visually depict the redistribution of configuration weights during the string breaking process, and reveal the observable recovery characteristics of the string after breaking. Further analysis shows that the enhancement of
quantum fluctuations can increase the weight of the double-
meson state configurations in the system wave function without changing the dominant dynamical behavior. The above results present a rich picture of string breaking dynamics in a one-dimensional Rydberg atomic chain and provide insights for studying confinement physics and related gauge field theory phenomena on
quantum simulation platforms.
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All authors Xin Liu, Han-Chao Chen, Zheng-Yuan Zhang, Jun Zhang, Ya-Jun Wang, Qing Li, Shi-Yao Shao, Bang Liu, Li-Hua Zhang, Dong-Sheng Ding, Bao-Sen Shi
Materials Science
Decoupling effects of the resistive-switching behavior on the polarization reversal in ultrathin ferroelectric Hf0.5Zr0.5O2 films
Chao Zhou, Sizhe Huang, Yangyang Si et al. (+10 more)
HfO2-based ferroelectric films have attracted considerable
attention as their nanoscale ferroelectricity and compatibility with cmos technology, fulfilling demands of emerging
memory technologies. However, as films scale down, resistive-switching behavior becomes increasingly pronounced, intricately intertwining with the polarization-switching process and affecting ferroelectric switching factors often overlooked yet crucial for device performance optimization. By characterizing resistive-switching behavior and oxygen vacancy motion using tailored electric pulse schemes, we decouple the resistive-switching behavior from the overall switching process in ultrathin ferroelectric HZO films, which would otherwise erroneously inflate polarization values and increase coercive fields. Building on this, we elucidate endurance degradation mechanisms from dual perspectives of resistive switching and defect migration. Furthermore, we demonstrate the mitigated resistive switching activity by designing HfO2-based devices with symmetric
oxide electrodes, achieving reduced coercive fields and improved cycling performances. This work provides crucial insights into the origins of inflated polarizations and reliability challenges in HfO2-based devices while offering a viable strategy to enhance ferroelectric properties for advanced
memory applications.
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All authors Chao Zhou, Sizhe Huang, Yangyang Si, Zhongqi Ren, Jianyuan Zhao, Hailin Wang, Jingxuan Li, Xianlong Cheng, Haoliang Huang, Shi Liu, Sujit Das, Shiqing Deng, Zuhuang Chen
Materials Science
Electronic band structure and exciton properties of $Pna2_1$ CaSnN$_2$
Ilteris K. Turan, Sarker Md. Sadman and Walter R. L. Lambrecht
The electronic band structure of CaSnN$_2$ in the wurtzite-based $Pna2_1$ structure is calculated using the Quasiparticle Self-consistent (QS)GW$^{BSE}$ method, including ladder diagrams in the screened Coulomb interaction W$^{BSE}$ and is found to have a direct gap of 2.59 eV at {\Gamma}, which corresponds to blue light wavelength of 478 nm and makes it an attractive candidate for sustainable blue light-emitting diodes (LEDs), avoiding Ga and In. The valence band splitting is analyzed in terms of
symmetry labeling, and the effective mass tensor is calculated for several bands at {\Gamma}. The valence band maximum has a1
symmetry and gives allowed transitions to the conduction band minimum for light polarized along the c-direction. While this is unfavorable for light emission with transverse electric (TE) or s-polarization from the basal plane, this would not be an impediment if another surface other than the basal plane is used. Furthermore, the
crystal field splitting between the $a_1$ and $b_1$ states, corresponding to polarizations along c and a respectively, reverses under an applied uniaxial tensile strain of 3.7% along the c direction, which might occur under biaxial compressive strain in the basal plane. The optical dielectric function, including electron-hole interaction effects is also reported, and the
excitons are analyzed, including several dark
excitons.
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