Quantum Gases
Deviations beyond the Kibble-Zurek mechanism in a Spin-Orbit-Coupled Bose-Einstein Condensate with phenomenological damping
Jun-Hang Ren, Sheng Liu and Yong-Sheng Zhang
We investigate the quench dynamics in a one-dimensional
spin-orbit-coupled Bose-Einstein condensate (SOC-BEC) across the phase transition from plane-wave (PW) to stripe (ST), incorporating phenomenological damping. In the dissipation-free case, a state stagnation phenomenon emerges during the PW-ST quench: for slow quenches, the system remains trapped in the PW phase due to the energy gap induced by critical slowing down, which prevents spontaneous relaxation to the stripe ground state. To explore this phenomenon and examine the universal scaling predicted by the Kibble-Zurek mechanism (KZM) in open systems, we introduce a dissipative Gross-Pitaevskii equation with a phenomenological damping term. Numerical simulations reveal that weak dissipation preserves the expected KZM power-law scaling for the freeze-out time and defect density, whereas strong dissipation or long quench times lead to significant deviations. Our results demonstrate that the KZM remains applicable in dissipative
quantum systems under appropriate conditions, providing insights into nonequilibrium dynamics in open
quantum systems.
Read the full abstract ▾
Materials Science
From Materials Database to Materials Bank: Assetizing Data for AI Driven Materials Innovation
Chenyao Ma, Di Zhang, Weibo Gong et al. (+9 more)
Driven by high-throughput experimentation, computational modeling, and artificial intelligence (AI), materials data has expanded at an unprecedented rate. Conventional materials databases function only as passive repositories, archiving raw experimental records indiscriminately including both successful and failed data, without systematic value filtering or asset management. This creates a critical gap between massive data accumulation and actionable innovation, hindering the identification of high-potential materials and industrial translation. To address this bottleneck, we propose an industrialization-oriented Materials Bank, a dedicated valuefiltering and assetization layer that operates beyond traditional databases. It does not merely curate high-quality data but systematically elevates qualified candidates into standardized, upgradable materials assets via a multi-dimensional BankCard framework covering scientific validity, synthesis feasibility, application readiness, and industrial value. By unifying databases, AI models, automated experimentation, and multi-criteria assessment into a cohesive closed-loop ecosystem, the Materials Bank establishes a clear trajectory from data to knowledge, candidate, asset, and product. It serves not as an enhanced database or screening tool, but as a decision infrastructure bridging academic discovery and industrial demand, offering a scalable paradigm to accelerate AI-driven materials innovation and deliver tangible real-world impact.
Read the full abstract ▾
All authors Chenyao Ma, Di Zhang, Weibo Gong, Wei Du, Rui Su, Yuhang Chen, Kan Xu, Huan Gu, Limin Li, Piao Ma, Zhenghao Li, Hao Li
Strongly Correlated Electrons
Ultrafast Fluence-Reversal Fingerprint of Fragile Kondo Hybridization in CePt$_2$In$_7$
Xin-Yi Tian, Qi-Yi Wu, Chen Zhang et al. (+13 more)
The emergence of heavy quasiparticles in a Kondo
lattice is usually viewed as the formation of a low-energy hybridization gap. Whether this gap represents a rigid electronic structure or a fragile many-body state that can be dynamically reconfigured remains a central question for heavy-
fermion systems near
magnetic order,
quantum criticality, and unconventional superconductivity. Here we use femtosecond pump-probe reflectivity to interrogate this problem in the weakly hybridized Kondo-
lattice compound CePt$_2$In$_7$. At low fluence, a slow quasiparticle relaxation channel emerges below $T^* \sim$ 40 K and follows a Rothwarf-Taylor bottleneck response with a low-energy recombination scale 2$\Delta \approx$ 7.4 meV. Coherent optical
phonons, independently identified by Raman spectroscopy, act as an internal
lattice thermometer and rule out large quasi-
equilibrium lattice heating as the origin of the nonlinear electronic response. The
phonon-free electronic amplitude $A_{\rm elec}$ reveals a fluence-reversal fingerprint: with cooling from the hybridization-crossover regime, the response evolves from weak-linear behavior to Rothwarf-Taylor-like bottleneck suppression and finally to anomalous high-fluence enhancement at the lowest temperatures. This reversal cannot be accounted for by a rigid fixed-gap bottleneck alone and instead identifies an ultrafast optical signature of photoinduced redistribution of a fragile Kondo-hybridized electronic response.
Read the full abstract ▾
All authors Xin-Yi Tian, Qi-Yi Wu, Chen Zhang, Hao Liu, Yang Luo, Bo Chen, Ying Zhou, Zhong-Tuo Fu, Jin-Dong Bai, Chun-Hui Lyu, Zi-Jie Xu, Hai-Long Deng, Hai-Yun Liu, Jun He, Yu-Xia Duan, Jian-Qiao Meng
Materials Science
Photon Statistics from Yb3+-Doped CsPbCl3 are Inconsistent with Quantum Cutting
Vincent R.M. Benning, Faris Horani, Daniel R. Gamelin et al. (+1 more)
CsPb(Cl1-xBrx)3:Yb3+ has been widely reported as a broadband
quantum-cutting material with a photoluminescence
quantum yield exceeding 100%, making it a promising candidate for enhancing the blue-green spectral response of silicon photovoltaics. Many groups have reproduced absolute photoluminescence
quantum yields over 100%, but others have struggled to obtain such high values. Here, we test the
quantum-cutting capabilities of CsPbCl3:Yb3+ nanocrystals and bulk material using
photon-correlation analysis. A
quantum-cutting material is expected to exhibit
photon bunching, but our experiments on CsPbCl3:Yb3+ show no such behavior. In fact, we observe the opposite – anti-bunching – under focused-excitation conditions. This observation can be explained with the previously established Auger-quenching pathway in CsPbCl3:Yb3+. Our results thus confirm high-power Auger quenching but question earlier descriptions of
quantum cutting in CsPb(Cl1-xBrx)3:Yb3+.
Read the full abstract ▾
All authors Vincent R.M. Benning, Faris Horani, Daniel R. Gamelin, Freddy T. Rabouw
Materials Science
Ultrafast magnetization induced by linearly polarized pulses is widespread in nonmagnetic semiconductors
Xiangzhou Zhu, Junfeng Qiao, Nicola Marzari et al. (+1 more)
Ultrafast optical on-off switching of
magnetic order promises near-petahertz information processing. Recently, it has been proposed that non-
magnetic semiconductors with narrow band edges or strong exchange interactions could display ultrafast magnetization when photoexcited with linearly polarized femtoseconds pulses, but the experimental detection of this effect remains a challenge, mostly for the lack of suitable candidate compounds. Here, we present a high-throughput first-principles screening of the MC3D database of experimentally known inorganic
crystals, identifying nearly 440 non-
magnetic semiconductors that develop
spin polarization under photoexcitation with linearly polarized pulses via a light-induced exchange-driven instability. We determine how the
crystal field environment and band-edge orbital character govern the magnitude and the type of
magnetic order of the photoinduced state and we unveil systematic chemical and periodic trends that provide intuitive guidance for materials selection. Our results argue that on-off switching of magnetization with linearly polarized femtosecond pulses is a widespread occurrence in non-
magnetic semiconductors, opening novel avenues for experimental verification and application.
Read the full abstract ▾
All authors Xiangzhou Zhu, Junfeng Qiao, Nicola Marzari, Matteo Calandra
Materials Science
Three-phonon mixing as a source of light-induced chirality
Y . Zhu, A. Vanderhaegen, Z. Zeng et al. (+7 more)
Mid- and far-infrared optical pulses have found wide applicability in experiments in which collective modes of solids are driven nonlinearly, as a means to manipulate functional properties of materials on ultrafast time scales. In the illustrative case of boron phosphate (BPO$_4$), mid-infrared excitation has been used to induce chirality in an otherwise achiral
crystal. The pump frequency dependence of photo-induced chirality reveals that, while on-resonance excitation is understood in terms of the well-documented
phonon rectification from two-
phonon mixing, additional pathways become relevant when the pump pulse is detuned from resonance. We find that a three-mode mixing mechanism becomes important in this case, whereas the contributions from other impulsive Raman terms are negligible. The results reported here provide a quantitative foundation for nonlinear phononic lineshapes in transparent materials, and open up new opportunities for
lattice control.
Read the full abstract ▾
All authors Y . Zhu, A. Vanderhaegen, Z. Zeng, M. Först, M. Fechner, C. Putzke, P. J. W. Moll, D. Prabhakaran, P. Radaelli, A. Cavalleri
Statistical Mechanics · Cross-listed from math-ph
Non-invertible symmetries and modular invariance in lattice models
Yacine Ikhlef
We consider classical 2d
lattice models with face interactions defined in terms of a fusion category. The
symmetries of such models typically include an
algebra of topological operators sitting on a closed path in the
lattice. In the case when the face interactions obey the Temperley-Lieb (TL) relations, we present a generic
algorithm to determine the decomposition of the transfer-
matrix space of states as a direct sum of simple TL modules. We apply this approach to several examples, and analyse the action of topological operators. As an application, we compute the modular transformation of the irreducible TL characters at primitive roots of unity.
Read the full abstract ▾
Strongly Correlated Electrons
Phonon-induced pseudogap phase in TiSe$_2$
Sotirios Fragkos, Nina Girotto Erhardt, Evgenia Symeonidou et al. (+9 more)
To comprehend
quantum ordered states, such as charge density waves (CDW), in layered transition metal dichalcogenides (TMDCs), it is essential to uncover their underlying normal states. Here, we use time- and angle-resolved extreme ultraviolet photoemission spectroscopy and ab initio electron-
phonon calculations to perform excited state band mapping of three prototypical 1T TMDCs, i.e., TiSe$_2$, HfTe$_2$, and ZrTe$_2$, at room temperature. The results reveal the profound impact of strong electron-
phonon-induced thermal fluctuations on the normal-phase electronic structure. Specifically, in the moderate electron-
phonon coupling regime, as in HfTe$_2$ and ZrTe$_2$, thermal fluctuations only lead to small spectral broadening and band renormalization. In the strongly coupled case, exemplified by TiSe$_2$, we observe soft-
phonon-induced, momentum-dependent suppression of spectral weight, i.e., pseudogaps - extending up to 1 eV above the
Fermi level. Our work establishes the normal phase of TiSe$_2$ as a
phonon-induced pseudogap phase governed by strong CDW fluctuations, thereby uncovering previously missing aspects of the TiSe$_2$ phase diagram, with broader implications for other TMDCs in the strong electron-
phonon coupling regime.
Read the full abstract ▾
All authors Sotirios Fragkos, Nina Girotto Erhardt, Evgenia Symeonidou, Hibiki Orio, Dominique Descamps, Stéphane Petit, Polychronis Tsipas, Kai Rossnagel, Jakub Schusser, Athanasios Dimoulas, Samuel Beaulieu, Dino Novko
Soft Condensed Matter · Cross-listed from physics.flu-dyn
Lagrangian velocity statistics of homogeneous isotropic turbulence in dilute polymer solutions
Yusuke Koide and Susumu Goto
We conduct direct numerical simulations of homogeneous isotropic
turbulence in dilute
polymer solutions to investigate the Lagrangian velocity statistics. We show how
polymers modulate the power spectral density of the Lagrangian velocity and the Lagrangian integral timescale by varying the Reynolds number, forcing method, and
polymer relaxation time. As the
polymer relaxation time increases, the attenuation of the power spectral density extends successively from high to low frequencies, and the Lagrangian integral timescale increases. To clarify the mechanism underlying the modulation of the Lagrangian velocity statistics, we decompose the Lagrangian velocity into the contributions from
vortices at different length scales. Using this scale-decomposition analysis, we demonstrate that the observed modulation of the Lagrangian velocity statistics results from
polymer-induced suppression of
vortices that proceeds from smaller to larger scales.
Read the full abstract ▾
Mesoscale and Nanoscale Physics
Orientation-tunable correlated Chern insulating states in chiral twisted double bilayer graphene proximitized by WSe2
Jiao Xie, Yongqin Xie, Fanqiang Chen et al. (+9 more)
Moire flat bands in
graphene systems proximitized by transition-metal dichalcogenides (TMDCs) provide a setting where
spin-orbit coupling (SOC) can reshape band
topology. The crystallographic
alignment angle twist angle between TMDC and
graphene layers is predicted to tune the balance of Ising and Rashba SOC, but a combined theoretical and experimental understanding of how twist angle governs the topological character of correlated states has not been systematically established. Here we show that in
chiral-stacked twisted double
bilayer graphene in proximity to WSe2, twist angle between
graphene and WSe2 determines the topological character of correlated Chern
insulators. Continuum model calculations reveal that Ising
spin-orbit coupling dominates at zero twist angle, giving rise to flat bands with finite valley Chern numbers, whereas Rashba coupling dominates at larger twist angle, resulting in topologically trivial bands. Transport measurements at quarter filling confirm this picture: twist angle = 0 deg devices exhibit C = +1 Chern
insulators, consistent with spontaneous isospin polarization, whereas twist angle = 15 degree devices show C = 0 despite exhibiting similar correlated insulating behavior. The sharp contrast establishes crystallographic
alignment as a new tuning knob, complementary to twist angle, displacement field, and carrier density, for engineering correlated topological states in van der Waals
heterostructures.
Read the full abstract ▾
All authors Jiao Xie, Yongqin Xie, Fanqiang Chen, Jiliang Yang, Sicheng Chen, Moyu Chen, Kenji Watanabe, Takashi Taniguchi, Shi-Jun Liang, Kemi Xu, Bin Cheng, Feng Miao
Mesoscale and Nanoscale Physics
Thermal rectification due to phonon confinement in nanoparticles
Alexej D. Semenov, Mariia Sidorova, Alessio Zaccone et al. (+1 more)
We demonstrate that thermal rectification can arise at the contact between two spherical nanoparticles of identical material but different size due to the
geometric confinement of
phonons. This confinement suppresses long-wavelength
phonons differently in differently sized particles and creates a size-dependent gap in the
phonon density of states. This gives rise to direction-dependent heat transport even in perfectly homogeneous materials. We develop an analytical model based on
phonon confinement and
phonon ray-tracing in the Casimir regime and derive expressions for heat fluxes and rectification efficiency as functions of particle sizes and temperatures. The model predicts measurable rectification efficiencies for nanoparticles with radii of a few tens of nanometers, reaching fraction of percent at room temperature and much larger values at low temperatures. The proposed mechanism provides a straightforward and scalable route to thermal rectification in granular nanomaterials without requiring material heterogeneity or strong nonlinearities.
Read the full abstract ▾
All authors Alexej D. Semenov, Mariia Sidorova, Alessio Zaccone, Marcel Di Vece
Materials Science
Kinetic Monte Carlo-Ising Machine Optimization for Atomistic Inverse Design of Solid Electrolytes
Ai Koizumi, Tomofumi Tada and Ryo Tamura
Maximizing ionic conductivity remains a fundamental challenge in the atomistic design of solid electrolytes. To this end, we present a framework that combines kinetic Monte Carlo (KMC) and factorization machine with quadratic-optimization annealing (FMQA), an Ising-machine-based black-box optimization
algorithm for large-scale combinatorial optimization. KMC evaluates the ionic conductivity for a given dopant configuration, whereas FMQA iteratively learns a surrogate model from a small configuration-conductivity
dataset and proposes configurations expected to maximize conductivity. To address the severe combinatorial explosion in large KMC simulation
cells, we partition the configuration space for parallel optimization. As a proof of concept, we apply this KMC-FMQA framework to bulk 8 mol % yttria-stabilized zirconia, identifying a dopant configuration with an order-of-magnitude higher conductivity than that of random configurations and the experimentally reported conductivity. Combined with experiments, this framework will enable the determination of microscopic structures from measured conductivity, providing insight into the underlying transport mechanisms.
Read the full abstract ▾
Materials Science
Symmetry-Enforced Ferroelectric Switching of Two-Dimensional Altermagnetism
Jiangyu Zhao, Yibo Liu, Guoli Wu et al. (+4 more)
Altermagnetism features strong momentum-dependent
spin splitting despite zero net magnetization, offering a transformative platform for next-generation spintronics. However, the nonvolatile and deterministic switching between its two equivalent
spin-splitting states remains a fundamental bottleneck. Here, we propose a universal layer-engineering paradigm to achieve
symmetry-enforced ferroelectric switching of two-dimensional altermagnetism. By sandwiching a conventional
antiferromagnetic monolayer between two identical ferroelectric layers, the out-of-plane polarization cleanly breaks the spatial
symmetry to induce robust altermagnetic splitting. Crucially, the global combined parity-time
symmetry dictates that reversing the ferroelectric polarization exactly inverts the altermagnetic
spin-splitting pattern. We rigorously validate this mechanism in the In2Se3/MnPTe3/In2Se3 trilayer using first-principles calculations. As a direct consequence, the ferroelectrically driven
spin-splitting reversal deterministically flips the anomalous
Hall effect signal, providing an unambiguous transport fingerprint to electrically distinguish the two altermagnetic states. Unconstrained by the stringent
symmetry requirements of intrinsic single-phase materials, our findings establish a versatile physical framework for electrically addressable altermagnetic spintronics.
Read the full abstract ▾
All authors Jiangyu Zhao, Yibo Liu, Guoli Wu, Xinru Li, Ying Dai, Baibiao Huang, Yandong Ma
Statistical Mechanics
Quantitative description of cognitive fatigue in repetitive monotonous tasks
Shahar Hod
There is strong qualitative empirical evidence in the scientific literature that, due to cognitive fatigue, workers performing repetitive and monotonous tasks are characterized by a gradual deterioration in their performance abilities as the time-on-task increases, a phenomenon known as the vigilance decrement. Using a time-dependent Sisyphus random climb model, we provide a quantitative description of this intriguing phenomenon. In particular, we use analytical techniques in order to determine the success probability function $S(t;{\cal N})$ of Sisyphus workers, the time-dependent fraction of workers who succeed, after making $t$ repetitive operations or less, to complete their task by making ${\cal N}$ successful operations in a row without a single fault in between. It is explicitly shown that the functional behavior of the increasing-in-time one-operation tumble probability $1-s(t)$ of exhausted Sisyphus workers may have a dramatic effect on the probability of the workers to achieve their ultimate goal in repetitive monotonous processes. In particular, we prove that the Sisyphus random climb model with the inverse power law functional behavior $s(t)\sim t^{-1/{\cal N}}$ of the one-operation success probability marks the boundary between Sisyphus workers whose success functions $S[t;s(t),{\cal N}]$ approach $1$ asymptotically in time (implying that all the workers eventually complete their task) and Sisyphus workers whose success functions approach an asymptotic value which is less than $1$, in which case some of the exhausted Sisyphus workers never complete their task successfully.
Read the full abstract ▾
Mesoscale and Nanoscale Physics
Observation of Intrinsic Anderson Localization in Few-Layer ReS$_2$
Shreya Paul, Pritam Das, Devarshi Chakrabarty et al. (+2 more)
Electron localization phenomena are expected to play an important role in the transport properties of two-dimensional materials. Rhenium disulfide (ReS$_2$), with its narrow conduction bandwidth, is uniquely susceptible to this effect. However, extrinsic disorder caused by fabrication methods obscures inherent localization behavior arising from reduced dimensionality and degrades transport properties. We report intrinsic Anderson localization in few-layer ReS$_2$ by eliminating extrinsic fabrication-induced disorder through all-dry van der Waals assembly and suppressing interface charge trapping through a hexagonal boron nitride (hBN) gate dielectric. Temperature-dependent transport reveals a crossover from nearest-neighbor hopping to two-dimensional (2D) Mott variable-range hopping (VRH). The non-monotonic gate-voltage dependence of activation energy provides direct access to the energy-resolved band-tail density of states of the ReS$_2$ conduction band. 2D Mott VRH yields a localization length of (3.5 $\pm$ 0.1) nm, an order of magnitude larger than disorder-dominated devices, providing a quantitative characterization of intrinsic Anderson localization in ReS$_2$.
Read the full abstract ▾
All authors Shreya Paul, Pritam Das, Devarshi Chakrabarty, Shamashis Sengupta, Sajal Dhara
Materials Science
High-Mobility and High-Reliability Top-Gate Oxide Semiconductor Transistors by Oxygen Engineering
Kai Jiang, Zhiyu Lin, Ziheng Wang et al. (+2 more)
In this work, we investigate the role of oxygen (O) on the performance of top-gate (TG) atomic-layer-deposited (ALD)
oxide semiconductor transistors. The results reveal distinct defect characteristics and positive bias temperature instability (PBTI) degradation mechanisms between oxygen-rich (O-rich) and oxygen-deficient (O-poor) devices. It is found that an O-rich device fabrication process followed by O-free annealing can effectively achieve TG indium-rich (In-rich)
oxide semiconductor transistors with high mobility, high reliability and high stability in hydrogen environment because O-rich process can suppress oxygen vacancies and their interaction with hydrogen, while O-free annealing plays a critical role in minimizing the formation of O-rich defects such as oxygen dimers (O-O bonds). Consequently, TG In-rich transistors with high mobility, steep subthreshold slope, and high PBTI reliability at high temperature are demonstrated. The understanding of O-rich defects provides a new insight to overcome the mobility-stability trade-off.
Read the full abstract ▾
All authors Kai Jiang, Zhiyu Lin, Ziheng Wang, Chen Wang, Mengwei Si
Mesoscale and Nanoscale Physics · Cross-listed from physics.optics
Unresolved-Sideband Optomechanics with Hexagonal Boron Nitride: Induced Transparency, Gain, and Frequency Combs
Francesco Fogliano, Thibaud Ruelle, David Jaeger et al. (+1 more)
Optomechanically induced transparency (OMIT) is usually modeled and studied in the resolved-sideband regime, but many compact microcavity platforms operate in the unresolved-sideband limit $(\kappa \gg \Omega_m)$. Here we investigate OMIT in this regime using a tunable fiber-based Fabry-Perot microcavity coupled to a suspended hexagonal boron nitride (hBN) drum resonator in a membrane-in-the-middle geometry. The system achieves a large single-
photon coupling rate of $g_0/2\pi \sim 180$ kHz and exhibits strong radiation-pressure backaction. By measuring OMIT spectra as a function of pump power and cavity detuning, we observe a crossover from a transparency-like dip to a gain feature in the reflected response. These maps are quantitatively reproduced by the full linearized optomechanical response, demonstrating the breakdown of the standard rotating-wave approximation used in the resolved-sideband limit. Finally, we drive the system into a nonlinear regime to generate optomechanical frequency combs. These results establish hBN fiber-cavities as a versatile architecture for unresolved-sideband optomechanics, nonlinear dynamics, and hybrid device integration.
Read the full abstract ▾
All authors Francesco Fogliano, Thibaud Ruelle, David Jaeger, Martino Poggio
Materials Science · Cross-listed from quant-ph
Atom diffraction in the strong-coupling regime
Carina Kanitz, Jakob Bühler, François Aguillon et al. (+6 more)
Analytic methods based on matter-wave diffraction are a cornerstone in condensed-matter research, providing access to static and dynamic materials properties down to the atomic level. In these experiments, the shape of the diffraction pattern is largely determined by the
lattice at
equilibrium whereas vibrationally-induced distortions are treated perturbatively. Here, we show that the perturbative approach does not hold for helium diffracted at kiloelectronvolt energy through freestanding single-layer
graphene. In this case, we enter a new regime of strong coupling where the projectile strongly interacts with the electron density of several
lattice atoms simultaneously, leading to phase shifts of several radians. In consequence,
lattice distortions introduce a significant phase spread that cannot be described by the typically employed Debye-Waller factor. We show that the weak-coupling regime is retained for atomic hydrogen diffraction. The experimental results are supported by simulations, providing a regime-independent approach to describe the influence of
phonons on atom diffraction phenomena.
Read the full abstract ▾
All authors Carina Kanitz, Jakob Bühler, François Aguillon, Vladimír Zobač, Jaime Glerum, Toma Susi, Maxime Debiossac, Philippe Roncin, Christian Brand
Statistical Mechanics · Cross-listed from cs.LG
Explaining Machine Learning and Memorization with Statistical Mechanics
Robin Theriault
Artificial neural networks (NNs) and machine learning (ML)
algorithms are poorly understood from a theoretical perspective, which makes it difficult to fully realize their potential and overcome their weaknesses. For instance, ML
algorithms train NN weights by moving them along a low-dimensional subspace of their allowed values, but this implicitly low-dimensional learning structure is not properly exploited to improve training because its nature is not well understood. Moreover, trained NNs are easily confused by pervasive
adversarial attacks whose theoretical underpinnings are still unclear. This thesis aims to improve our theoretical understanding of NNs and ML, with a particular focus on
adversarial attacks and implicitly low-dimensional learning. For this purpose, we use mathematical tools from statistical mechanics to study different types of NNs and ways in which they can fit the data. In particular, we study two classes of models that fit the data with various degrees of learning and memorization: dense associative
memory (DAM) and restricted Boltzmann machines (RBM). In the process, we investigate connections between different versions of these models that are useful to make analytical investigations more efficient.
Read the full abstract ▾
Mesoscale and Nanoscale Physics
Andreev reflection mediated by topological corner states in a two-dimensional honeycomb lattice
Kai-Tong Wang, Yunjin Yu, Fuming Xu et al. (+1 more)
Topological corner states in two-dimensional second-order topological
insulators (SOTIs) are localized in real space. We numerically demonstrate that such localized topological corner states can mediate Andreev reflection when coupled to a superconducting lead. We consider a transport setup based on a two-dimensional honeycomb
lattice, consisting of a normal lead, a central SOTI region, and a superconducting lead. The central SOTI region is described by the modified Kane–Mele model with an in-plane Zeeman field and hosts topological corner states in a diamond-shaped flake. Although the central region is insulating, the local density of states shows that incident electrons can turn the localized corner state into an extended scattering state, which forms a resonant tunneling channel to the superconducting lead. This process leads to a perfect Andreev reflection peak near zero energy. Away from this resonance, antiresonance dips appear in the Andreev reflection spectrum, and their positions can be tuned by the Zeeman field strength. We show that the suppression of Andreev reflection is caused by
quantum interference and the imbalance between electron and hole dwell times in the central region. These results demonstrate that topological corner states can provide a resonant tunneling path to the superconducting interface and mediate Andreev reflection in second-order topological systems.
Read the full abstract ▾
All authors Kai-Tong Wang, Yunjin Yu, Fuming Xu, Jian Wang
Strongly Correlated Electrons
Nonlinear topological laser based on multipole insulators
Zi-Yuan Li, Zi-Xiang Hu and Qi Li
Two-dimensional higher-order topological
insulators (HOTIs), characterized by distinctive one-dimensional edge states and zero-dimensional corner states, provide an ideal platform for developing higher-order topological
lasers. In this work, we systematically investigate the two-dimensional Benalcazar-Bernevig-Hughes (BBH) model, which hosts quantized quadrupole moments and topologically protected corner and edge states. By confining the lasing mode to selected topological corner or edge states under controlled gain, we demonstrate that the stable light excitation achieved after long-time
evolution is predominantly determined by the topological properties of the model
Hamiltonian. To characterize the system's topological features, we introduce several diagnostic ratios: the corner decay ratio $\tau_{1}$ and edge-to-corner ratio $\tau_{2}$ quantify the localization degree and spatial extent of corner states, respectively, while the inter-corner transfer ratio $\chi$ measures the intensity transfer efficiency mediated by coherent edge-state dynamics. The abrupt changes in $\tau_{1}$ and $\tau_{2}$ as functions of the hopping parameter $\gamma/\lambda$ directly reveal topological phase transitions, providing a comprehensive toolkit for extracting topological signatures from the system's dynamical
evolution. Additionally, modulating the
lattice site parity enables flexible tuning of corner state localization positions, offering insights for device engineering. Our calculations reveal that achieving bistability between corner states and edge states is relatively challenging.
Read the full abstract ▾
Soft Condensed Matter
Beyond binary scission: a generalized three-species cascade breakage model for wormlike micellar solutions
Rongxin Lu, Jiwei Jia and Young Ju Lee
Wormlike micellar fluids exhibit complex rheological behavior driven by the continuous breakage and recombination of self-assembled micellar networks. Existing two-species models provide a coarse binary representation of the micellar population, limiting their ability to resolve intermediate structural states and broad relaxation spectra. To address this limitation, we develop a three-species cascade breakage model consisting of gel-network, long chains, and short chains. By introducing an intermediate micellar state, the model links the rapid relaxation of short fragments to the slow recovery of the gel-network within a unified kinetic framework. This additional structural pathway gives rise to a three-mode viscoelastic response, improves the high-frequency description of the dynamic
moduli, and produces a non-monotone constitutive curve that evolves into a stress plateau with coexisting shear bands in Couette flow. This cascade mechanism also governs the transient response, including stress overshoot, hysteresis, and multistep relaxation after shear cessation. Overall, the proposed three-species model provides a physically interpretable framework for worm-like micellar shear banding, capturing the connection between cascade microstructural
evolution, broad relaxation dynamics, and macroscopic flow localization.
Read the full abstract ▾
Materials Science
Hidden ordered compound-layer and its tailoring of the electronic/optical property in Ge2Sb2SexTe5-x alloys
Chenxu Yu, Linggang Zhu, Hanyu Liu et al. (+4 more)
Ge2Sb2SexTe5-x (GSST)
alloys represent an emerging class of phase-change materials for integrated photonics. However, the microscopic origins underlying their superior performance compared to the parent compound Ge2Sb2Te5 remain elusive. By using atomic simulations, this work elucidates that the thermal stability and low optical loss of GSST are fundamentally governed by the formation of an in-layer compound-like structure with SeTe2 or Se2Te stoichiometry depending on the Se content, contrasting to the previously believed pure-element-layered model where Se and Te atoms occupy separate layers inside GSST. The newly identified compound-layered structures maintaining stability at temperature above 370 K, yield an enlarged bandgap, weakened antibonding character, and more importantly, a moderate refractive index as well as decreased extinction coefficient which align better with the experiment compared to the previously believed model. The present findings not only help bridge the long-standing theory-experiment gap regarding the optical properties of GSST by redefining its atomic structure, but also establish local chemical ordering as a critical materials design principle for high-performance photonics.
Read the full abstract ▾
All authors Chenxu Yu, Linggang Zhu, Hanyu Liu, Xianyao Huan, Naihua Miao, Jian Zhou, Zhimei Sun
Mesoscale and Nanoscale Physics
Yongqin Xie, Jian Wang, Moyu Chen et al. (+13 more)
Exploring exotic
quantum metallic states beyond Landau's
Fermi liquid theory remains a central focus in condensed matter physics. Such non-
Fermi liquid behavior is mostly observed near
quantum criticality, yet growing
attention is directed toward extended NFL phases with intrinsic
quantum fluctuations rooted in the extended ground state. While these extended NFL states have been previously reported only in a limited set of d- and f-electron systems, realizing a single, highly tunable platform capable of exhibiting multiple resistance exponent values is essential for uncovering the connection between the resistance exponent and the dominant
quantum fluctuations coupled to quasiparticles. However, corresponding experimental progress remains elusive. Here, we report the observation of tunable extended non-
Fermi liquid behavior in twisted double
bilayer graphene encapsulated by aligned hBN layers. This NFL phase spans a broad range of carrier densities and exhibiting a carrier density dependent resistance exponent. Combined with temperature dependent resistance, magnetotransport and differential resistance measurements, these findings support a scenario where strong
quantum fluctuations emerge from the interplay between localized and itinerant carriers. Our work establishes a highly tunable platform beyond conventional frameworks to investigate the organizing principles of non-
Fermi liquid physics manifested in diverse behaviors.
Read the full abstract ▾
All authors Yongqin Xie, Jian Wang, Moyu Chen, Chen Zhao, Fanqiang Chen, Qiao Li, Sicheng Chen, Jiao Xie, Kenji Watanabe, Takashi Taniguchi, Jin-hua Gao, Rui Wang, Shi-Jun Liang, Chunming Yin, Bin Cheng, Feng Miao
Strongly Correlated Electrons
Investigation of the $J_1$-$J_2$ Heisenberg model on the triangular lattice: A study with projected entangled-pair states
Litao Ma, Wei-Lin Tu, Didier Poilblanc et al. (+1 more)
The nature of the
quantum spin liquid (QSL) phase in the frustrated $J_1$-$J_2$ Heisenberg model on the triangular
lattice remains an open and actively debated problem. In this work, we employ the infinite projected entangled-pair state (PEPS) to systematically investigate the model under different
symmetry constraints. Our simulations reveal a direct transition from the $120^\circ$ Néel state to a putative QSL at $J_2/J_1\approx 0.08$, signaled by the collapse of
magnetic order. We further show that, through either an appropriate
unitary rotation or spontaneous
spin long-range order, the stripe
antiferromagnetic phase can also be accurately captured within the infinite PEPS framework. A central focus of our study is the role played by the PEPS
symmetry in approximating the QSL ground-state sandwiched between the two
magnetic phases. We first found that a fully-symmetric topological $\mathbb{Z}_2$ Resonating Valence Bond state, which can be written as a simple PEPS with bond dimension $D=3$, exhibits a reasonably good variational energy. Motivated by this finding, we have further constructed generic $\mathbb{Z}_2$-symmetric PEPS of larger bond dimension (up to $D=7$). We found that, under wavefunction optimization, spinons condense and, simultaneously, topological vison excitations get confined, hence precluding $\mathbb{Z}_2$ topological order. This strongly indicates the gapless (or critical) nature of the QSL phase, which is most naturally consistent with a U(1) Dirac
spin liquid scenario.
Read the full abstract ▾
All authors Litao Ma, Wei-Lin Tu, Didier Poilblanc, Ji-Yao Chen
Soft Condensed Matter
Self-consistent field theory of semiflexible nematics: Density-nematic coupling, anisotropic elasticity, and defect core sizes
Longyu Qing and Jorge Viñals
The linear response of wormlike chains in the nematic phase is studied by self-consistent field theory. The model
Hamiltonian incorporates Maier–Saupe orientational interactions together with an isotropic excluded volume interaction. The latter models implicitly solvent mediated chain interactions, as appropriate for a lyotropic nematic. An effective free energy description for uniform nematic states is constructed in terms of the chain segment density and uniaxial nematic order parameter, providing a unified framework for density–degree of order coupling, isotropic-nematic coexistence, and the limit of stability of the nematic phase. Our results show that strong density–nematic degree of order coupling can destabilize the nematic state. The location of the instability depends on the ratio of excluded volume and nematic interaction, $u_0/u_2$. In contrast, director distortions couple to density and nematic order variations only at higher order, remaining effectively decoupled in the linear response regime. The Frank elastic constants and the correlation lengths are obtained from a linear response analysis based on the self-consistent field theory free energy. Increasing flexibility strongly suppresses twist and bend elasticity while affecting splay elasticity comparatively weakly, leading to a crossover from bend-dominated to splay-dominated elasticity. The correlation lengths and Frank elastic anisotropy obtained from the linear response analysis explain well director profiles around a +1/2 disclination core, including the core size. The latter is proportional to the
equilibrium correlation length, in agreement with Landau–de Gennes scaling.
Read the full abstract ▾
Quantum Gases · Cross-listed from nlin.PS
Controllable Thouless Pumping Switching Dynamics of Gap Solitons Mediated by Finite Bogoliubov Excitations
Tao Jiang, Jie Liu and Li-Chen Zhao
We investigate the Thouless pumping dynamics of nonlinear gap
solitons and attempt to realize topological Chern number switching by modulating nonlinear parameters and varying the ramping rate of the relative phase between periodic potentials. We find that gap
solitons can undergo nonlinear instabilities accompanied by finite Bogoliubov excitations under near-adiabatic ramping. Such finite Bogoliubov excitations induce the particle loss of the
solitons, leading to reversed propagation directions that signals the occurrence of Chern number switching with analyzing the correspondence between
soliton chemical potential and Bloch topological energy band. Our findings offer a feasible strategy for manipulating the Thouless pump dynamics of gap
solitons mediated by finite Bogoliubov excitations, with implications for topological
quantum transport and
quantum computing applications.
Read the full abstract ▾
Other Condensed Matter · Cross-listed from hep-th
Phase Transition and Censorship Principle for Holographic Casimir Effect
Zhen-Rui Huang and Rong-Xin Miao
This paper explores the
holographic Casimir effect associated with parallel spherical defects. The
gravity dual is dominated by the AdS
soliton with connected EOW branes at small widths, transitioning to AdS space with disconnected EOW branes as the width increases. Consequently, the
holographic Casimir effect undergoes a first-order phase transition and vanishes in the disconnected phase. This new behavior highlights a significant difference from free theories,
holographic parallel plane defects, and
hyperbolic defects. Additionally, we confirm that the free theories adhere to the
holographic bound for the Casimir effect in the case of parallel spherical defects. Interestingly, we observe that
cosmic censorship provides a
holographic interpretation of the attractive nature of the Casimir force when identical boundary conditions are imposed on both parallel surfaces. The repulsive Casimir force is associated with the bulk spacetime containing a naked singularity, which is generally considered forbidden. Additionally, we argue that topological censorship offers a natural explanation for why the
vacuum of parallel defects is dual to the AdS
soliton.
Read the full abstract ▾
Strongly Correlated Electrons
The competition between low-temperature kinks and magnons at the vicinity of the deconfinement transition point in 1D easy-axis XXZ ferromagnet
P. N. Bibikov
Studying the ordered phases and
quantum supercritical low-temperature regime at the vicinity of the deconfinement transition point in 1D easy-axis XXZ ferromagnet, we suggest their interpretations according to the corresponding dominant lowest-energy excitations. We show, that the two ordered phases are governed by
magnons, while the
quantum supercritical regime is governed by kinks. Within this framework the Ising model is treated in detail.
Read the full abstract ▾