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arXiv 2024年

作者： Cao, Kaiyuan Tong, Peiqing Zhejiang Lab Hangzhou311100 China Department of Physics Institute of Theoretical Physics Nanjing Normal University Nanjing210023 China Jiangsu Key Laboratory for Numerical Simulation of Large Scale Complex Systems Nanjing Normal University Nanjing210023 China

We investigate the nonequilibrium dynamics induced by a finite-time linear quench in the XY chain. Initially, we examine the dynamical quantum phase transition, characterized by the nonanalytic behavior of the Loschmidt amplitude. We find distinct behaviors of DQPTs during and following the ramp. Following the ramp, the ramp crossing the critical point hc is the sufficient condition for the occurrence of DQPT, but it is not during the ramp. Through AIA approximation analysis, we establish that adequate distancing from the critical point is crucial for DQPT manifestation during the ramp, elucidating the absence of DQPT as the ramp gets faster. Additionally, we explore another type of dynamical phase transition, describing the long-term relaxation behavior of the order parameter. Our finding indicates that the asymptotic behavior of the time-dependent part induced by the linear quench is equivalent to that following a sudden quench, i.e., time-dependent part exhibits power-law decays of ∼ t−3/2 and ∼ t−1/2 for the ramp to the commensurate and incommensurate phases, respectively. Moreover, we also delve into the steady part, which showcases nonanalytic singularities at the critical point. Copyright © 2024, The Authors. All rights reserved.

关键词： Phase transitions

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Quantum Phase Transitions in the Alternating Xy Chain with Three-Site Interactions

SSRN

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SSRN 2024年

作者： Cao, Kaiyuan Fu, Hao Liu, Xue Zhong, Ming Tong, Peiqing Zhejiang Lab Hangzhou311100 China Department of Physics Institute of Theoretical Physics Nanjing Normal University Nanjing210023 China Jiangsu Key Laboratory for Numerical Simulation of Large Scale Complex Systems Nanjing Normal University Nanjing210023 China

We investigate the quantum phase transition in the alternating XY chain with the XZX+YZY type of three-spin interactions. We present the exact solution derived by means of the Jordan-Wigner transformation and study the average magnetization, spin correlations, and von Neumann entropy to establish the phase diagram. The phase diagram consists of the ferromagnetic phases, the paramagnetic phases, and the phase with weak magnetization (WM). By examining the nearest-neighbor transverse spin correlation, we probe that in the WM phase, the spins within a supercell generate a cluster with a small total spin, but between the nearest-neighbor supercells are distributed randomly. Especially for the dimerized limit case, the spins within a supercell tend to point to opposite directions of the transverse field. In addition, we also investigate the influence of the three-site interaction, and find that the WM phase is absent as the strength of the three-site interaction increases. © 2024, The Authors. All rights reserved.

关键词： Magnetization

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Quantum phase transitions in the alternating XY chain with three-site interactions

arXiv

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arXiv 2024年

关键词： Magnetization

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Fermi-Energy-Sensitive Universal Conductance Fluctuations in Anisotropic Materials

arXiv

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arXiv 2025年

作者： Yang, Qiang Hu, Yayun Hou, Zhe Tong, Peiqing School of Physics and Technology Nanjing Normal University Nanjing210023 China Zhejiang Lab Hangzhou311100 China Ministry of Education Key Laboratory of Numerical Simulation of Large Scale Complex Systems Nanjing Normal University Nanjing210023 China

Universal conductance fluctuations (UCF) are a hallmark of quantum interference in mesoscopic devices. According to the Altshuler-Lee-Stone theory, the amplitude of UCF remains independent of system parameters such as Fermi energy and disorder strength. However, recent experiments have demonstrated a significant variation in UCF with respect to Fermi energy in the anisotropic Dirac semimetal Cd3As2, suggesting a dependence on band anisotropy. In this work, we reconcile the discrepancy between theoretical predictions and experimental observations through a detailed study of UCF versus Fermi energy using a tight-binding model with tunable anisotropy parameters. Near the band edge, the Hamiltonian is simplified to an anisotropic free electron gas model, recovering the generalized Altshuler-Lee-Stone theory. However, as the Fermi energy shifts toward the band center, where rotational symmetry breaks into C4 (four-fold rotational) symmetry, the UCF amplitude deviates from the standard theory. Our findings reveal that UCF becomes increasingly sensitive to Fermi energy as the anisotropy grows stronger. Furthermore, using realistic parameters for Cd3As2, our calculations demonstrate an increase in UCF away from the Dirac point, in qualitative agreement with experimental results. The enhancement of UCF occurs in two perpendicular transport directions that we have calculated, albeit with quantitative differences in magnitude, which can be tested in future experiments. Given the prevalence of anisotropic materials and technical advances in engineering anisotropy through strain or twist, our results offer a valuable reference for characterizing intrinsic electronic properties via UCF. © 2025, CC BY.

关键词： Anisotropic media

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Semileptonic decays B/Bs→(D^(?),D^(?)s)lνl in the PQCD approach with the lattice QCD input

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Chinese Physics C 2020年第5期44卷 8-21页

作者： Xue-Qing Hu Su-Ping Jin Zhen-Jun Xiao Department of Physics and Institute of Theoretical Physics Nanjing Normal UniversityNanjing 210023China Jiangsu Key Laboratory for Numerical Simulation of Large Scale Complex Systems Nanjing Normal UniversityNanjing 210023China

We study the semileptonic B/Bs→(D^(?),D^(?)s)lνl decays in the framework of the Standard Model(SM),by employing the perturbative QCD(PQCD)factorization formalism combined with the lattice QCD input for the relevant transition form *** calculate the branching ratios B(B(s)→D^(?)(s)lνl)with l=(e,μ,τ),the ratios of the branching fractions R(D^(?))and R(D^(?)s),and the physical observables Pτ(D^(?)(s)),FL(D?(s))and AFB(τ).The“PQCD+Lattice”predictions for B(B→D^(?)lνl)and R(D^(?))agree with the available experimental measurements within *** the ratios R(Ds)and R(D^?s),the"PQCD+Lattice"predictions agree with the other *** Pτ(D^?)and FL(D^?),our theoretical predictions agree with the measured values within *** theoretical predictions of the semileptonic B/Bs decays considered could be tested in the near future by the LHCb and Belle II experiments.

关键词： semileptonic decays form factor PQCD Bs meson

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Semileptonic decays B_c■(η_c, J/ψ)l■_l in the “PQCD+Lattice” approach

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Chinese Physics C 2020年第2期44卷 51-61页

We study the semileptonic decaysBc-→(ηc,J/ψ)l-■lusing the PQCD factorization approach with the newly defined distribution amplitudes of the B c meson and a new kind of parametrization for extrapolating the form factors which takes into account the recent lattice QCD *** find the following main results:(a)the PQCD predictions of the branching ratios of theBc→(ηc,J/ψ)l■decays are smaller by about 5%-16%when the lattice results are taken into account in the extrapolation of the relevant form factors;(b)the PQCD predictions of the ratio Rηc,RJ/ψand of the longitudinal polarization PτareRηc=0.34±0.01,RJ/ψ=0.28±0.01,Pτ(ηc)=0.37±0.01and Pτ(J/ψ)=-0.55±0.01;and(c)after including the lattice results,the theoretical predictions slightly change:Rηc=0.31±0.01,RJ/ψ=0.27±0.01,Pτ(ηc)=0.36±0.01andPτ(J/ψ)=-0.53±*** theoretical predictions of RJ/ψagree with the measurements within the *** other predictions could be tested by the LHCb experiment in the near future.

关键词： semileptonic Bc decays PQCD approach lattice QCD results ratio of branching ratios longitudinal polarization

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Effects of infinite-range interaction on the localization properties of one-dimensional disordered harmonic chains

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Physical Review B 2023年第2期108卷 024202-024202页

作者： Wanwan Shi Peiqing Tong School of Physics and Technology Nanjing Normal University Nanjing 210023 People's Republic of China Jiangsu Key Laboratory for Numerical Simulation of Large Scale Complex Systems Nanjing Normal University Nanjing 210023 People's Republic of China and Nanjing Normal University Taizhou College Taizhou 225300 People's Republic of China

We study the effects of infinite-range (IR) interaction on the localization properties of one-dimensional disordered harmonic chains. Two kinds of disordered models are considered: one is with disordered masses, but constant spring coefficient (mass model), and the other is with disordered spring coefficient, but constant mass (spring model). It is found that the IR interaction induces a gap between the ω=0 and the excited frequency band for both types of disordered models, and their gaps are both proportional to the IR interaction coefficient γ for larger γ. In addition, the width of the excited frequency band of the mass model is also proportional to γ for larger γ, while that of the spring model is independent of γ. By employing the normalized participation ratio, we find that the low-frequency modes of the mass model except for the lowest frequency change from extended to localized states, while the localized properties of the spring model modes remain unchanged. We also discuss the effects of IR interaction on the dynamic behaviors of the two kinds of disordered models.

关键词： Lattice dynamics Localization Long-range interactions Phonons 1-dimensional systems Disordered systems

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Topological properties and localization transition in a one-dimensional non-Hermitian lattice with a slowly varying potential

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Physical Review B 2022年第10期105卷 104201-104201页

作者： Siqing Li Mengyao Li Yi Gao Peiqing Tong Center for Quantum Transport and Thermal Energy Science Jiangsu Key Laboratory on Opto-Electronic Technology School of Physics and Technology Nanjing Normal University Nanjing 210023 China Jiangsu Key Laboratory for Numerical Simulation of Large Scale Complex Systems School of Physics and Technology Nanjing Normal University Nanjing 210023 China

We explore the eigenenergy distribution, localization transition, and topological property of a one-dimensional non-Hermitian lattice with a slowly varying potential, which does not possess parity-time (PT) symmetry. We found that, in contrast to PT-symmetric systems whose eigenenergies can stay real until the PT-symmetry breaking point, the eigenenergies in the present system are fully complex and their distribution in the complex plane depends on the parameters. As non-Hermiticity is introduced into the system, also depending on the parameters, the eigenstates may show a crossover behavior from fully extended to fully localized as non-Hermiticity is increased, or there will be a sharp localization transition at finite non-Hermiticity. Nevertheless, this non-Hermitian system is proven to be topologically trivial, thus we conclude that in general non-Hermitian systems, the localization transition is not always of a topological nature.

关键词： Anderson localization Topological phase transition Non-Hermitean systems PT-symmetry

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Resonance contributions from χc0 in the charmless three-body hadronic B meson decays

arXiv

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arXiv 2023年

作者： Zhang, Ya-Lan Wang, Chao Lin, Yi Xiao, Zhen-Jun Faculty of Mathematics and Physics Huaiyin Institute of Technology Jiangsu Huaian223200 China Department of Physics Institute of Theoretical Physics Nanjing Normal University Jiangsu Nanjing210023 China Jiangsu Key Laboratory for Numerical Simulation of Large Scale Complex Systems Nanjing Normal University Jiangsu Nanjing210023 China

Within the framework of perturbative QCD factorization, we investigate the nonfactorizable contributions to these factorization-forbidden Quasi-two-body decays B(s) → hχc0 → hπ+π−(K+K−) with h = π,K. We compare our predicted branching ratios for the B(s) → Kχc0 → Kπ+π−(K+K−) decay with available experiment data as well as predictions by other theoretical studies. The branching ratios of these decays are consistent with data and other theoretical predictions. In the Cabibbo-suppressed decays B(s) → hχc0 → hπ+π−(K+K−) with h = K¯0,π, however, the values of the branching ratios are the order of 10−7 and 10−8. The ratio Rχc0 between the decay B+ → π+χc0 → π+π+π− and B+ → K+χc0 → K+π+π− and the distribution of branching ratios for different decay modes in invariant mass are considered in this work. © 2023, CC BY.

关键词： Factorization

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Interfacial Thermal Transport and Energy Dissipation in Multilayer PdSe2 Field Effect Transistors

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Advanced Materials 2025年第0期 e2503264页

作者： Xie, Jiaqiu Yu, Zehao Sun, Yuanchen Gan, Qikang Liu, Chenhan Wang, Lei Zhang, Lifa Zhao, Yunshan Phonon Engineering Research Center of Jiangsu Province Ministry of Education Key Laboratory of NSLSCS Center for Quantum Transport and Thermal Energy Science Institute of Physics Frontiers and Interdisciplinary Sciences School of Physics and Technology Nanjing Normal University Nanjing210023 China National Laboratory of Solid-State Microstructures School of Physics Collaborative Innovation Center of Advanced Microstructures Nanjing University Nanjing210093 China Micro- and Nano-scale Thermal Measurement and Thermal Management Laboratory Jiangsu Key Laboratory for Numerical Simulation of Large-Scale Complex Systems School of Energy and Mechanical Engineering Nanjing Normal University Nanjing210046 China

The continuous miniaturization of 2D electronic circuits results in increased power density during device operation, leading to heat localization and placing higher demands on their performance thresholds. The risk to thermal breakdown and subsequent damage, due to the energy dissipation in the 2D semiconductor field-effect transistors (FETs) supported on the bulk substrates, represents a significant challenge in maintaining their optimal performance. Herein, this study investigates energy dissipation behavior in multilayer PdSe2 FETs for the first time. The high-field breakdown behavior is firstly studied in multilayer PdSe2 FETs on SiO2/Si substrates, where a maximum current density of ≈2.74 MA cm−2 is observed, which is comparable to that of multilayer black phosphorus FET and significantly higher—by about five times—than that of multilayer MoS2 FET. Additionally, the thermal boundary conductance (TBC) of PdSe2/SiO2 interface is measured at room temperature using Raman thermometry. The TBC is found to be ≈12–13 MW m−2 K−1, which is relatively low compared to the other known solid–solid interfaces, indicating that enhancing the performance of PdSe2 FETs can be possible by optimizing the TBC at the PdSe2/SiO2 interface. These findings provide valuable insights for design of high-quality and high-performance PdSe2 electronic and optoelectronic devices. © 2025 Wiley-VCH GmbH.

关键词： Multilayers

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