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arXiv 2025年

作者： Gan, Yanbiao Zhuang, Zhaowen Yang, Bin Xu, Aiguo Zhang, Dejia Chen, Feng Song, Jiahui Wu, Yanhong Hebei Key Laboratory of Trans-Media Aerial Underwater Vehicle North China Institute of Aerospace Engineering Langfang065000 China School of Energy and Safety Engineering Tianjin Chengjian University Tianjin300384 China National Key Laboratory of Computational Physics Institute of Applied Physics and Computational Mathematics P. O. Box 8009-26 Beijing100088 China National Key Laboratory of Shock Wave and Detonation Physics Mianyang621999 China HEDPS Center for Applied Physics and Technology College of Engineering Peking University Beijing100871 China State Key Laboratory of Explosion Science and Technology Beijing Institute of Technology Beijing100081 China School of Physical Science and Technology Guangxi University Nanning530004 China School of Aeronautics Shan Dong Jiaotong University Jinan250357 China School of Aerospace Engineering Beijing Institute of Technology Beijing100081 China

Supersonic flow is a typical nonlinear, nonequilibrium, multiscale, and complex phenomenon. Compared to scenarios described by Navier-Stokes (NS) theory, mesoscale behavior in supersonic flow exhibits greater discreteness and a higher degree of nonequilibrium. Meanwhile, the entropy production mechanism, which involves compression efficiency and the ability to perform external work, is a significant focus in supersonic flow fields. As the degree of discrete/nonequilibrium effects increases, the study of entropy production based on NS theory may need reevaluation and appropriate revision. To address these issues, this paper develops and applies the discrete Boltzmann modeling and analysis method/model (DBM), based on kinetic and mean-field theories, to simulate, and analyze these phenomena. The study provides the following results: A Burnett-level DBM suitable for supersonic flow is constructed based on the Shakhov-BGK model. Higher-order analytical expressions for typical thermodynamic nonequilibrium effects are derived, providing a constitutive basis for improving traditional macroscopic hydrodynamics modeling. Criteria for evaluating the validity of DBM are established by comparing numerical and analytical solutions of nonequilibrium effects. The multiscale DBM is used to investigate discrete/nonequilibrium characteristics and entropy production mechanisms in shock regular reflection. The findings include: (a) Compared to the NS-level DBM, the Burnett-level DBM offers more accurate representations of viscous stress and heat flux, i.e., more precise dissipative mechanisms, ensures non-negativity of entropy production in accordance with the second law of thermodynamics, and exhibits better numerical stability. (b) Near the interfaces of incident and reflected shock waves, strong nonequilibrium driving forces lead to prominent nonequilibrium effects. By monitoring the timing and location of peak nonequilibrium quantities, the evolution characteristics of incident and

关键词： Supersonic flow

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Implementation of scalable suspended superinductors

arXiv

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arXiv 2024年

作者： Jünger, Christian Chistolini, Trevor Nguyen, Long B. Kim, Hyunseong Chen, Larry Ersevim, Thomas Livingston, William Koolstra, Gerwin Santiago, David I. Siddiqi, Irfan Department of Physics University of California BerkeleyCA94720 United States Applied Mathematics and Computational Research Division Lawrence Berkeley National Laboratory BerkeleyCA94720 United States Materials Science Division Lawrence Berkeley National Laboratory BerkeleyCA94720 United States

Superinductors have become a crucial component in the superconducting circuit toolbox, playing a key role in the development of more robust qubits. Enhancing the performance of these devices can be achieved by suspending the superinductors from the substrate, thereby reducing stray capacitance. Here, we present a fabrication framework for constructing superconducting circuits with suspended superinductors in planar architectures. To validate the effectiveness of this process, we systematically characterize both resonators and qubits with suspended arrays of Josephson junctions, ultimately confirming the high quality of the superinductive elements. In addition, this process is broadly compatible with other types of superinductors and circuit designs. Our results not only pave the way for scalable novel superconducting architectures but also provide the primitive for future investigation of loss mechanisms associated with the device substrate. Copyright © 2024, The Authors. All rights reserved.

关键词： Qubits

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Large non-reciprocal charge transport in Pt2MnGe up to room temperature

arXiv

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arXiv 2022年

作者： Meng, Kangkang Wang, K. Zhang, N.N. Fu, Z.G. Chen, J.K. Wu, Y. Xu, X.G. Miao, J. Jiang, Y. School of Materials Science and Engineering University of Science and Technology Beijing Beijing100083 China Institute of Applied Physics and Computational Mathematics Beijing China

Non-reciprocal charge transport that is strongly associated with the structural or magnetic chirality of the quantum materials system is one of the most exotic properties of condensed matter physics. Here, using magnetic alloys film Pt2MnGe, we have realized the large non-reciprocal charge transport up to room temperature, which roots in the organic combination of chirality dependent carrier scattering and special magnetic configurations. In this framework, the conduction electrons are scattered asymmetrically by the emerging non-zero vector spin chirality under in-plane magnetic field, resulting in robust non-reciprocal response. More astonishingly, the vector spin chirality in Pt2MnGe film can be reversed by a spin-polarized current through spin Hall effect in a junction with Pt layer. Our work resolves the general limitation of non-reciprocal charge transport to cryogenic temperatures, and paves the way for extending its applications in the emerging field of chiral spintronics. © 2022, CC BY.

关键词： Quantum chemistry

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Dynamics of particles near the surface of amedium under ultra-strong shocks

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Matter and Radiation at Extremes 2021年第2期6卷 46-53页

作者： Zixiang Yan Hao Liu Xinyu Zhang Guoli Ren Jie Liu Wei Kang Weiyan Zhang Xiantu He HEDPS Center for Applied Physics and Technologyand School of PhysicsPeking UniversityBeijing 100871China Department of Applied Physics School of Physics and ElectronicsHunan UniversityChangsha 410082China HEDPS Center for Applied Physics and Technologyand College of EngineeringPeking UniversityBeijing 100871China Institute of Applied Physics and Computational Mathematics Beijing 100088China Graduate School China Academy of Engineering PhysicsBeijing 100193China China Academy of Engineering Physics Mianyang 621900China

Through nonequilibrium molecular dynamics simulations,we provide an atomic-scale picture of the dynamics of particles near the surface of a medium under ultra-strong *** shows that the measured surface velocity v_(f)under ultra-strong shocks is actually the velocity of the critical surface at which the incident probe light is reflected,and v_(f)has a single-peaked *** doubling rule commonly used in the case of relatively weak shocks to determine particle velocity behind the shock front is generally not valid under ultra-strong *** a short period of acceleration,v_(f)exhibits a long slowly decaying tail,which is not sensitive to the atomic mass of the medium.A scaling law for v_(f)is also proposed,and this may be used to improve the measurement of particle velocity u in future experiments.

关键词： structure. surface doubling

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POINTWISE ESTIMATES FOR THE FUNDAMENTAL SOLUTIONS OF HIGHER ORDER SCHRÖDINGER EQUATIONS IN ODD DIMENSIONS II: HIGH DIMENSIONAL CASE

arXiv

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arXiv 2024年

作者： Cheng, Han Huang, Shanlin Huang, Tianxiao Zheng, Quan Institute of Applied Physics and Computational Mathematics Beijing100088 China School of Mathematics and Statistics Hubei Key Laboratory of Engineering Modeling and Scientific Computing Huazhong University of Science and Technology Hubei Wuhan430074 China Sun Yat-sen University Guangdong Zhuhai519082 China School of Mathematics and Statistics Huazhong University of Science and Technology Hubei Wuhan430074 China

In this paper, for any odd n and any integer m ≥ 1 with n > 4m, we study the fundamental solution of the higher order Schrödinger equation i∂tu(x, t) = ((−∆)m + V(x))u(x, t), t ∈ R, x ∈ Rn, where V is a real-valued C n+21 −2m potential with certain decay. Let Pac(H) denote the projection onto the absolutely continuous spectrum space of H = (−∆)m+V, and assume that H has no positive embedded eigenvalue. Our main result says that e−itHPac(H) has integral kernel K(t, x, y) satisfying n(m−1) |K(t, x, y)| ≤ C(1 + |t|)−(2nm −σ)(1 + |t|− 2nm ) (1 + |t|− 21m |x − y|)− 2m−1 , t , 0, x, y ∈ Rn, where σ = 2 if 0 is an eigenvalue of H, and σ = 0 otherwise. A similar result for smoothing operators H 2αm e−itHPac(H) is also given. The regularity condition V ∈ C n+21 −2m is optimal in the second order case, and it also seems optimal when m > 1. © 2024, CC0.

关键词： Schrodinger equation

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Obtaining Intense Attosecond Pulses in the Far Field from Relativistic Laser-Plasma Interactions

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Physical Review applied 2021年第2期16卷 024042-024042页

作者： Y. Zhang C. L. Zhong S. P. Zhu X. T. He M. Zepf B. Qiao Center for Applied Physics and Technology HEDPS and SKLNPT School of Physics Peking University Beijing 100871 China Institute of Applied Physics and Computational Mathematics Beijing 100094 China Helmholtz Institute Jena 07743 Jena Germany

In this paper, we show that the Gouy phase shift plays a key role in the far-field waveform evolution of the reflected harmonic radiations from plasma surfaces driven by a relativistic Gaussian laser. With a proper adjustment of laser focal position away from the plasma surface, the inherent separations between the peaks of different harmonic carrier waves as well as the fundamental wave due to different wavelengths can be cleared away when they propagate from near to far field, since they experience the same Gouy phase shift of π/2. Using this method, intense attosecond pulses can be obtained in the far field with no need of any spectral filters. Three-dimensional particle-in-cell simulations show that far-field attosecond pulses with intensity of 4×1015W/cm2 (2.56×1017W/sr; 65 times increase) and duration of 76as (50% decrease) can be obtained by lasers at intensities of 1021W/cm2. Such brilliant pulses with fully reserved spectra significantly benefit applications in attosecond science.

关键词： High-energy-density plasmas High-order harmonic generation Laser-plasma interactions Ultrafast phenomena X-ray generation in plasmas

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Comparative study on atomic ionization in bicircular laser fields by length and velocity gauges S-matrix theory

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Chinese physics B 2020年第2期29卷 254-261页

作者： Hong Xia Xin-Yan Jia Xiao-Lei Hao Li Guo Dai-He Fan Gen-Bai Chu Jing Chen School of Physical Science and Technology Southwest Jiaotong UniversityChengdu 610031China Institute of Theoretical Physics and Department of Physics Shanxi UniversityTaiyuan 030006China State Key Laboratory for Quantum Optics and Center for Cold Atom Physics Shanghai Institute of Optics and Fine MechanicsChinese Academy of SciencesShanghai 201800China Science and Technology on Plasma Physics Laboratory Laser Fusion Research CenterChina Academy of Engineering PhysicsMianyang 621900China HEDPS Center for Applied Physics and TechnologyPeking UniversityBeijing 100871China Institute of Applied Physics and Computational Mathematics Beijing 100088China

Ionization of atoms in counter-rotating and co-rotating bicircular laser fields is studied using the S-matrix theory in both length and velocity *** show that for both the bicircular fields,ionization rates are enhanced when the two circularly polarized lights have comparable *** addition,the curves of ionization rate versus the field amplitude ratio of the two colors for counter-rotating and co-rotating fields coincide with each other in the length gauge case at the total laser intensity 5×10^14 W/cm^2,which agrees with the experimental ***,the degree of the coincidence between the ionization rate curves of the two bicircular fields decreases with the increasing field amplitude ratio and decreasing total laser *** the help of the ADK theory,the above characteristics of the ionization rate curves can be well interpreted,which is related to the transition from the tunneling to multiphoton ionization mechanism.

关键词： above-threshold ionization(ATI) bicircular laser fields length gauge velocity gauge S-matrix theory

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Suppressing electron disorder-induced heating of ultracold neutral plasma via optical lattice

arXiv

引用

arXiv 2023年

作者： Wang, HaiBo Yao, Zonglin Zhou, Fuyang Wu, Yong Wang, Jianguo Chen, Xiangjun Hefei National Research Center for Physical Sciences The Microscale Department of Modern Physics University of Science and Technology of China Anhui Hefei230026 China Hefei National Laboratory University of Science and Technology of China Anhui Hefei230088 China Institute of Applied Physics and Computational Mathematics Beijing100088 China

Disorder-induced heating (DIH) prevents ultracold neutral plasma into electron strong coupling regime. Here we propose a scheme to suppress electronic DIH via optical lattice. We simulate the evolution dynamics of ultracold neutral plasma constrained by three-dimensional optical lattice using classical molecular dynamics method. The results show that for experimentally achievable condition, electronic DIH is suppressed by a factor of 1.3, and the Coulomb coupling strength can reach to 0.8 which is approaching the strong coupling regime. Suppressing electronic DIH via optical lattice may pave a way for the research of electronic strongly coupled plasma. Copyright © 2023, The Authors. All rights reserved.

关键词： Optical lattices

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POINTWISE ESTIMATES FOR THE FUNDAMENTAL SOLUTIONS OF HIGHER ORDER SCHRÖDINGER EQUATIONS IN ODD DIMENSIONS I: LOW DIMENSIONAL CASE

arXiv

引用

arXiv 2024年

In this paper, for any odd n and any integer m ≥ 1 with n tu(x, t) = ((−∆)m + V(x))u(x, t), t ∈ , x ∈ n, where V is a real-valued potential with certain decay. Let Pac(H) denote the projection onto the absolutely continuous spectrum space of H = (−∆)m + V, and assume that H has no positive embedded eigenvalue. Our main result says that e−itHPac(H) has integral kernel K(t, x, y) satisfying (Equation presented), where the constants C, h > 0, and h can be specified by m, n and the zero energy resonances of H. A similar result for smoothing operators like (Equation presented) is also given. One of the main novelties lies in a new and unified approach to obtain the asymptotic expansions of perturbed resolvents under various types of zero energy resonances. © 2024, CC0.

关键词： Schrodinger equation

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Localization measures of parity adapted U(D)-spin coherent states applied to the phase space analysis of the D-level Lipkin-Meshkov-Glick model

引用

Physical Review E 2023年第2期108卷 024107-024107页

作者： Alberto Mayorgas Julio Guerrero Manuel Calixto Department of Applied Mathematics University of Granada Fuentenueva s/n 18071 Granada Spain Department of Mathematics University of Jaen Campus Las Lagunillas s/n 23071 Jaen Spain Institute Carlos I of Theoretical and Computational Physics (iC1) University of Granada Fuentenueva s/n 18071 Granada Spain

We study phase space properties of critical, parity symmetric, N-qudit systems undergoing a quantum phase transition (QPT) in the thermodynamic N→∞ limit. The D=3 level (qutrit) Lipkin-Meshkov-Glick model is eventually examined as a particular example. For this purpose, we consider U(D)-spin coherent states (DSCS), generalizing the standard D=2 atomic coherent states, to define the coherent state representation Qψ (Husimi function) of a symmetric N-qudit state |ψ〉 in the phase space CPD−1 (complex projective manifold). DSCS are good variational approximations to the ground state of an N-qudit system, especially in the N→∞ limit, where the discrete parity symmetry Z2D−1 is spontaneously broken. For finite N, parity can be restored by projecting DSCS onto 2D−1 different parity invariant subspaces, which define generalized “Schrödinger cat states” reproducing quite faithfully low-lying Hamiltonian eigenstates obtained by numerical diagonalization. Precursors of the QPT are then visualized for finite N by plotting the Husimi function of these parity projected DSCS in phase space, together with their Husimi moments and Wehrl entropy, in the neighborhood of the critical points. These are good localization measures and markers of the QPT.

关键词： Phase diagrams Potential energy surfaces Quantum information theory Quantum phase transitions Quantum statistical mechanics Quantum many-body systems Group theory Many-body techniques Phase space methods

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