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Quasiparticle picture for high-harmonic generation in correlated electron systems

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Physical Review B 2023年第15期108卷 155125-155125页

作者： Kai Huang Tao-Yuan Du School of Mathematics and Physics China University of Geosciences Wuhan 430074 China Hubei Key Laboratory of Optical Information and Pattern Recognition Wuhan Institute of Technology Wuhan 430205 China Key Laboratory of Computational Physical Sciences (MOE) Fudan University Shanghai 200433 China

The key optical and electronic functionalities in condensed materials are determined by the band filling of electrons and their Coulomb correlations. To directly capture how many-body correlations influence the correlated electron dynamics under the driving of laser pulses, the comprehensible quasiparticle picture is desired to distinguish the ultrafast creation and annihilation of doublon-holon pairs in attosecond timescale. Here, we adopt the one-dimensional non-half-filling Hubbard model to study the high-harmonic generation (HHG) in correlated electron systems. As the value of Hubbard U increases, the cutoff energy and spectral features in HHG spectra have been revealed and their scaling laws are explained by the characteristic energy gaps obtained from the electronic bands under the quasiparticle picture. The adjustable degree of band filling in correlated systems paves a way to enhance high-harmonic emissions by regulating the creation of doublon-holon pairs. The complex temporal profile of HHG is elucidated in this work by the light-induced evolution of quasiparticle bands in correlated materials. In addition, the dephasing of the HHG spectrum caused by the vibration-induced disorder or lattice temperature is affirmed in the correlated electron systems and this dephasing process is attributed to quasiparticle-lattice scattering during the doublons and holons propagating among the disordered lattice sites.

关键词： High-order harmonic generation Strongly correlated systems Hubbard model Tight-binding model

Designing Optimized Topologies for On-Chip Massive Data Communication 22

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Designing Optimized Topologies for On-Chip Massive Data Comm...

22nd IEEE International Conference on High Performance Computing and Communications, 18th IEEE International Conference on Smart City and 6th IEEE International Conference on Data Science and Systems, HPCC-SmartCity-DSS 2020

作者： Liu, Weifeng Wu, Linping Xu, Xiaowen Guo, Meng Institute of Applied Physics and Computational Mathematics Beijing Beijing China Jinan China

ISBN: (纸本)9781728176499

Now more processing elements are laid on a single chip to process massive data concurrently, and the on-chip networks thus are becoming more and more important. As contention for communication resources has strong impact on the execution of a parallel program, and it is difficult to get the communication pattern of an application in advance, the parallel program needs to have good performance under any stochastic task mapping strategy. This manuscript presents a new method for designing new on-chip network topologies and gives theoretical analysis to the designed topologies. The analysis results show that compared with some classical topologies, although the designed topologies have lower vertex degrees, they can achieve good properties in terms of network diameter, average latency, and throughput. If we take advantage of higher levels of VLSI process and increase the vertex degree, we can design topologies with even better communication properties. Simulation results show that the designed topologies can significantly improve the performance of parallel applications. © 2020 IEEE.

关键词： Network topology

Stiffened gas approximation and GRP resolution for fluid flows of real materials

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arXiv 2021年

作者： Wang, Yue Li, Jiequan Laboratory of Computational Physics Institute of Applied Physics and Computational Mathematics Beijing100088 China HEDPS Center for Applied Physics and Technology College of Engineering Peking University Beijing100871 China

The equation of state (EOS) embodies thermodynamic properties of compressible fluid materials and usually has very complicated forms in real engineering applications, subject to the physical requirements of thermodynamics. The complexity of EOS in form gives rise to the difficulty in analyzing relevant wave patterns. Concerning the design of numerical algorithms, the complex EOS causes the inefficiency of Riemann solvers and even the loss of robustness, which hampers the development of Godunov-type numerical schemes. In this paper, a strategy of local stiffened gas approximation is proposed for real materials. The stiffened gas EOS is used to approximate general EOS locally at each interface of computational control volumes so that the Riemann solver can be significantly simplified. In the meantime, the generalized Riemann problem (GRP) solver is adopted not only for high resolution purpose but effective reflection of the local thermodynamics as well. The resulting scheme is demonstrated to be efficient and robust and numerical examples display the excellent performance of such an approximation. Copyright © 2021, The Authors. All rights reserved.

关键词： Thermodynamic properties

The role of double ionization on the generation of doubly charged ions in copper vacuum arcs: Insight from particle-in-cell/direct simulation Monte Carlo methods

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arXiv 2021年

作者： Yang, Wei Zhou, Qianhong Sun, Qiang Yang, Wenyuan Dong, Zhiwei Institute of Applied Physics and Computational Mathematics Beijing100094 China

Metal vapour vacuum arcs are capable to generate multiply charged metallic ions, which are widely used in fields such as ion deposition, ion thrusters, and ion sources, etc. According to the stationary model of cathode spot, those ions are generated by electron-impact single ionization in a step-wise manner, which is M -> M+ -> M2+ -> ... mainly. This paper is designed to study quantitatively the role of double ionization M -> M2+ in the breakdown initiation of copper vacuum arcs. A direct simulation Monte Carlo (DSMC) scheme of double ionization is proposed and incorporated into a 2D particle-in-cell (PIC) method. The super-particles of Cu2+ ions generated from different channels are labelled independently in the PIC-DSMC modelling of vacuum arc breakdown. The cathode erosion rate based on PIC modelling is about 40μg/C in arc burning regime, which agrees well with previous experiments. The temporal discharge behaviours such as arc current, arc voltage, and ionization degree of arc plasma, are influenced with or without double ionization negligibly. However, additional Cu2+ ions are generated near the cathode in breakdown initiation from the double ionization channel, with a lower kinetic energy on average. Therefore, the results on spatial distribution and energy spectra of Cu2+ ions are different with or without double ionization. This paper provides a quantitative research method to evaluate the role of multiply ionization in vacuum arcs. © 2021, CC BY.

关键词： Copper

Exploring Novel 2D Analogues of Goldene: Electronic, Mechanical, and Optical Properties of Silverene and Copperene

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arXiv 2025年

作者： dos Santos, Emanuel J.A. Alves, Rodrigo A.F. Dias, Alexandre C. Pereira, Marcelo L. Galvão, Douglas S. Ribeiro, Luiz A. University of Brasília Institute of Physics Federal District Brasília70910-900 Brazil Computational Materials Laboratory LCCMat Institute of Physics University of Brasília Federal District Brasília70910-900 Brazil Institute of Physics International Center of Physics University of Brasília Federal District Brasília70919-970 Brazil University of Brasília College of Technology Department of Electrical Engineering Federal District Brasília70910-900 Brazil Department of Applied Physics Center for Computational Engineering and Sciences State University of Campinas Campinas São Paulo13083-859 Brazil

Two-dimensional (2D) materials have garnered significant attention due to their unique properties and broad application potential. Building on the success of goldene, a monolayer lattice of gold atoms, we explore its proposed silver and copper analogs, silverene and copperene, using density functional theory calculations. Our findings reveal that silverene and copperene are energetically stable, with formation energies of -2.3 eV/atom and -3.1 eV/atom, closely matching goldene’s -2.9 eV/atom. Phonon dispersion and ab initio molecular dynamics simulations confirm their structural and dynamical stability at room temperature, showing no bond breaking or structural reconfiguration. Mechanical analyses indicate isotropy, with Young’s moduli of 73 N/m, 44 N/m, and 59 N/m for goldene, silverene, and copperene, respectively, alongside Poisson’s ratios of 0.46, 0.42, and 0.41. These results suggest comparable rigidity and deformation characteristics. Electronic band structure analysis highlights their metallic nature, with variations in the band profiles at negative energy levels. Despite their metallic character, these materials exhibit optical properties akin to semiconductors, pointing to potential applications in *** Codes 00-xx © 2025, CC BY.

关键词： Poisson ratio

Quantitative phase imaging through an ultra-thin lensless fiber endoscope

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Light(Science & Applications) 2022年第8期11卷 1843-1852页

作者： Jiawei Sun Jiachen Wu Song Wu Ruchi Goswami Salvatore Girardo Liangcai Cao Jochen Guck Nektarios Koukourakis Juergen W.Czarske Laboratory of Measurement and Sensor System Technique(MST) TU DresdenHelmholtzstrasse 1801069DresdenGermany Competence Center for Biomedical Computational Laser Systems(BIOLAS) TU DresdenDresdenGermany State Key Laboratory of Precision Measurement Technology and Instruments Department of Precision InstrumentsTsinghua University100084BeijingChina Institute for Integrative Nanosciences IFW DresdenHelmholtzstraße 2001069DresdenGermany Max Planck Institute for the Science of Light&Max-Planck-Zentrum für Physik und Medizin 91058ErlangenGermany Cluster of Excellence Physics of Life TU DresdenDresdenGermany Institute of Applied Physics TU DresdenDresdenGermany

Quantitative phase imaging(QPI)is a label-free technique providing both morphology and quantitative biophysical information in ***,applying such a powerful technique to in vivo pathological diagnosis remains ***-core fiber bundles(MCFs)enable ultra-thin probes for in vivo imaging,but current MCF imaging techniques are limited to amplitude imaging *** demonstrate a computational lensless microendoscope that uses an ultra-thin bare MCF to perform quantitative phase imaging with microscale lateral resolution and nanoscale axial sensitivity of the optical path *** incident complex light field at the measurement side is precisely reconstructed from the far-field speckle pattern at the detection side,enabling digital refocusing in a multi-layer sample without any mechanical *** accuracy of the quantitative phase reconstruction is validated by imaging the phase target and hydrogel beads through the *** the proposed imaging modality,three-dimensional imaging of human cancer cells is achieved through the ultra-thin fiber endoscope,promising widespread clinical applications.

关键词： fiber phase thin

RELAXATION SCHEMES FOR ENTROPY DISSIPATIVE SYSTEM OF VISCOUS CONSERVATION LAWS

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arXiv 2023年

作者： Chen, Tuowei Li, Jiequan Institute of Applied Physics and Computational Mathematics Beijing100088 China Multidisciplinary Studies Capital Normal University Beijing100048 China State Key Laboratory for Turbulence Research and Complex System Peking University Beijing100871 China

In this paper, we introduce a hyperbolic model for entropy dissipative system of viscous conservation laws via a flux relaxation approach. We develop numerical schemes for the resulting hyperbolic relaxation system by employing the finite-volume methodology used in the community of hyperbolic conservation laws, e.g., the generalized Riemann problem method. For fully discrete schemes for the relaxation system of scalar viscous conservation laws, we show the asymptotic preserving property in the coarse regime without resolving the relaxation scale and prove the dissipation property by using the modified equation approach. Further, we extend the idea to the compressible Navier-Stokes equations. Finally, we display the performance of our relaxation schemes by a number of numerical experiments. Copyright © 2023, The Authors. All rights reserved.

关键词： Entropy

Successive Picket Drive for Mitigating the Ablative Richtmyer–Meshkov Instability

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Chinese physics Letters 2019年第2期36卷 28-31页

作者： Meng Li Wen-Hua Ye Institute of Applied Physics and Computational Mathematics Center for Applied Physics and Technology HEDPS Peking University

The ablative Richtmyer–Meshkov instability(ARMI) is crucial to the successful ignition implosion of the inertial confinement fusion(ICF) because of its action as the seed of the Rayleigh–Taylor instability. In usual ICF implosions, the first shock driven by various foots of the pulses plays a central role in the ARMI growth. We propose a new scheme for refraining from ARMI with a pulse of successive pickets. With the successive-picket pulse design, a rippled capsule surface is compressed by three successive shocks with sequentially strengthening intensities and ablated stabilization, and the ablative Richtmyer–Meshkov growth is mitigated quite *** numerical simulations and theoretical analyses identify the validity of this scheme.

关键词： RMI ICF Successive Picket Drive for Mitigating the Ablative Richtmyer Meshkov Instability

Nonlinear bubble behaviours of compressible Rayleigh–Taylor instability with isothermal stratification in cylindrical geometry

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arXiv 2025年

作者： Yuan, Ming Zhao, Zhiye Liu, Luoqin Wang, Pei Liu, Nan-Sheng Lu, Xi-Yun Department of Modern Mechanics University of Science and Technology of China Anhui Hefei230026 China Department of Mechanical and Aerospace Engineering The Hong Kong University of Science and Technology Hong Kong Institute of Applied Physics and Computational Mathematics Beijing100094 China

Nonlinear evolutions of two-dimensional single-mode compressible Rayleigh–Taylor instability (RTI) with isothermal stratification are investigated in cylindrical geometry via direct numerical simulation for different Atwood numbers (AT = 0.1 − 0.9) and Mach numbers (Ma = 0.1 − 0.9). It is found that the nonlinear bubble growth involves the effects of density stratification, vorticity accumulation and flow compressibility and shows considerable differences between convergent (acceleration acting radially inward) and divergent (acceleration acting radially outward) cases. Specifically, the density stratification leads to non-acceleration at low AT and high Ma. The accelerations in convergent cases are dominated by vorticity accumulation at low AT and low Ma and by flow compressibility at high AT and high Ma whereas the accelerations in divergent cases are purely induced by flow compressibility at high AT and high Ma. Based on the nonlinear theory of incompressible cylindrical RTI with uniform-density background (Zhao et al., J. Fluid Mech., vol. 900, 2020, A24), an improved model is proposed by taking the density variation, vorticity accumulation and flow compressibility into consideration. This model is verified by numerical results and well reproduces the bubble evolution for different AT and Ma from linear to highly nonlinear regimes. © 2025, CC BY.

关键词： Vorticity