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Observation of Strong and Weak Thermalization in a Superconducting Quantum Processor

Physical Review Letters 2021年第2期127卷 020602-020602页

作者： Fusheng Chen Zheng-Hang Sun Ming Gong Qingling Zhu Yu-Ran Zhang Yulin Wu Yangsen Ye Chen Zha Shaowei Li Shaojun Guo Haoran Qian He-Liang Huang Jiale Yu Hui Deng Hao Rong Jin Lin Yu Xu Lihua Sun Cheng Guo Na Li Futian Liang Cheng-Zhi Peng Heng Fan Xiaobo Zhu Jian-Wei Pan Hefei National Laboratory for Physical Sciences at Microscale and Department of Modern Physics University of Science and Technology of China Hefei Anhui 230026 China Shanghai Branch CAS Center for Excellence and Synergetic Innovation Center in Quantum Information and Quantum Physics University of Science and Technology of China Shanghai 201315 China Shanghai Research Center for Quantum Sciences Shanghai 201315 China Institute of Physics Chinese Academy of Sciences Beijing 100190 China School of Physical Sciences University of Chinese Academy of Sciences Beijing 100190 China Theoretical Quantum Physics Laboratory RIKEN Cluster for Pioneering Research Wako-shi Saitama 351-0198 Japan Songshan Lake Materials Laboratory Dongguan 523808 Guangdong China CAS Center for Excellent in Topological Quantum Computation University of Chinese Academy of Sciences Beijing 100190 China

We experimentally study the ergodic dynamics of a 1D array of 12 superconducting qubits with a transverse field, and identify the regimes of strong and weak thermalization with different initial states. We observe convergence of the local observable to its thermal expectation value in the strong-thermalizaion regime. For weak thermalization, the dynamics of local observable exhibits an oscillation around the thermal value, which can only be attained by the time average. We also demonstrate that the entanglement entropy and concurrence can characterize the regimes of strong and weak thermalization. Our work provides an essential step toward a generic understanding of thermalization in quantum systems.

关键词： Eigenstate thermalization Quantum simulation Quantum statistical mechanics Spin dynamics 1-dimensional spin chains Superconducting qubits

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Coulomb Instabilities of a Three-Dimensional Higher-Order Topological Insulator

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Physical Review Letters 2021年第17期127卷 176601-176601页

作者： Peng-Lu Zhao Xiao-Bin Qiang Hai-Zhou Lu X. C. Xie Shenzhen Institute for Quantum Science and Engineering and Department of Physics Southern University of Science and Technology (SUSTech) Shenzhen 518055 China Shenzhen Key Laboratory of Quantum Science and Engineering Shenzhen 518055 China International Center for Quantum Materials School of Physics Peking University Beijing 100871 China CAS Center for Excellence in Topological Quantum Computation University of Chinese Academy of Sciences Beijing 100190 China Beijing Academy of Quantum Information Sciences West Building 3 No. 10 Xibeiwang East Road Haidian District Beijing 100193 China

Topological insulators (TIs) are an exciting discovery because of their robustness against disorder and interactions. Recently, second-order TIs have been attracting increasing attention, because they host topologically protected 1D hinge states in 3D or 0D corner states in 2D. A significantly critical issue is whether the second-order TIs also survive interactions, but it is still unexplored. We study the effects of weak Coulomb interactions on a 3D second-order TI, with the help of renormalization-group calculations. We find that the 3D second-order TIs are always unstable, suffering from two types of topological phase transitions. One is from second-order TI to TI, the other is to normal insulator. The first type is accompanied by emergent time-reversal and inversion symmetries and has a dynamical critical exponent κ=1. The second type does not have the emergent symmetries but has nonuniversal dynamical critical exponents κ<1. Our results may inspire more inspections on the stability of higher-order topological states of matter and related novel quantum criticalities.

关键词： Topological insulators Topological phase transition Renormalization group

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Absolute triple differential cross sections for low-energy electron impact ionization of biochemically relevant systems: Water, tetrahydrofuran, and hydrated tetrahydrofuran

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Physical Review A 2021年第1期104卷 012817-012817页

作者： Jiaqi Zhou Esam Ali Maomao Gong Shaokui Jia Yutian Li Yingying Wang Zhen Zhang Xiaorui Xue Dmitry V. Fursa Igor Bray Xiangjun Chen Don Madison Alexander Dorn Xueguang Ren School of Physics Xi'an Jiaotong University Xi'an 710049 China Max-Planck-Institut für Kernphysik Saupfercheckweg 1 69117 Heidelberg Germany Department of Natural Sciences D. L. Hubbard Center for Innovation Northwest Missouri State University Maryville Missouri 64468 USA Department of Physics Faculty of Arts & Sciences-El Marj University of Benghazi El Marj Libya Hefei National Laboratory for Physical Sciences at Microscale and Department of Modern Physics University of Science and Technology of China Hefei Anhui 230026 China Synergetic Innovation Center of Quantum Information and Quantum Physics University of Science and Technology of China Hefei Anhui 230026 China Curtin Institute for Computation and Department of Physics and Astronomy Curtin University GPO Box U1987 Perth WA 6845 Australia Department of Physics Missouri University of Science and Technology Rolla Missouri 65409 USA

An experimental procedure is reported, which provides the absolute triple differential cross sections (ATDCSs) for electron-impact ionization of large (bio)molecules. This type of measurements represents the most stringent tests for new or existing theoretical models. We will use this procedure to test the accuracy of the best currently available theoretical models for the problems of electron-impact (65 eV) ionization of the molecules water (H2O), tetrahydrofuran (C4H8O), and their hydrogen-bonded dimer H2O·C4H8O. The cross sections were calculated using the molecular three-body distorted-wave (M3DW) model, the multicenter three-distorted-wave (MCTDW) approach, and the multicenter three-distorted-wave using the Ward-Macek approximation (MCTDW-WM). When compared to the new experimental ATDCS results which cover almost the full solid angle of the ejected electron and a broad range of ejected electron energies and projectile scattering angles, it is found that the data for water are generally well reproduced by the M3DW model, while strong deviations in the absolute magnitude of the cross sections are found for the MCTDW. The MCTDW-WM model provides improved agreement over the MCTDW. These theoretical models, however, become less adequate for the ATDCS of C4H8O, in particular concerning the absolute magnitude. Furthermore, we find that a water environment can play a noticeable role for the ionization dynamics in the case of hydrated molecules.

关键词： Electron & positron scattering Electronic excitation & ionization

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Experimental Observation of Momentum-Space Chiral Edge Currents in Room-Temperature Atoms

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Physical Review Letters 2019年第2期122卷 023601-023601页

作者： Han Cai Jinhong Liu Jinze Wu Yanyan He Shi-Yao Zhu Jun-Xiang Zhang Da-Wei Wang Interdisciplanery Center for Quantum Information Department of Physics and State Key Laboratory of Modern Optical Instrumentation Zhejiang University Hangzhou 310027 China State Key Laboratory of Quantum Optics and Quantum Optics Devices Institute of Opto-Electronics Shanxi University Taiyuan 030006 China Synergetic Innovation Center of Quantum Information and Quantum Physics University of Science and Technology of China Hefei Anhui 230026 China CAS Center of Excellence in Topological Quantum Computation University of Chinese Academy of Sciences Beijing 100190 China

Chiral edge currents play an important role in characterizing topological matter. In atoms, they have been observed at such a low temperature that the atomic motion can be measured. Here we report the first experimental observation of chiral edge currents in atoms at room temperature. Staggered magnetic fluxes are induced by the spatial phase difference between two standing-wave light fields, which couple atoms to form a momentum-space zigzag superradiance lattice. The chiral edge currents are measured by comparing the directional superradiant emissions of two timed Dicke states in the lattice. Our results pave the way for simulating topological physics in hot atoms.

关键词： Effects of atomic coherence on light propagation Electromagnetically induced transparency Synthetic gauge fields Coherent control

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Geometries, Stabilities and Electronic Properties Study of Small Xnk(X=Mn, Fe, Co;N=1-8) Clusters Studied by Density Functional Theory

SSRN

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SSRN 2024年

作者： Shi, Shunping Wan, Mingjie Fan, Zhixiang Diao, Kai Chen, Deliang Computational Physics Key Laboratory of Sichuan Province YiBin University Yibin644000 China College of Mathematics and Physics Chengdu University of Technology Chengdu610059 China School of science Key Laboratory of High Performance Scientific Computation Xihua University Chengdu610039 China Chengdu Technological University Yibin Campus Yibin644000 China School of Physics and Electronic Guizhou Education University Guiyang550018 China

The geometry, relative stability, chemical activity, and magnetic properties of XnK(X=Mn, Fe, Co;n=1-8) clusters have been systematically investigated using quantum calculations of LANL2DZ basis sets at the PBE1PBE level. By optimizing different structural isomers, we determined the ground state structure of XnK(X=Mn, Fe, Co;n=1-8) clusters, which tends to be compact as the cluster size increases. In order to study the stability of clusters, the average binding energies, dissociation energies and second-order difference of total energies of the ground state structure are calculated. The results show that the stability of FenK clusters is comparable to that of ConK clusters, and both are higher than that of MnnK clusters. Finally, the chemical activity and magnetic properties of the clusters are discussed. The dissociation energies, second-order difference of total energies, HOMO-LUMO energy gaps, and magnetic moments of the ground-state clusters show an irregular oscillatory behavior with atomic number. © 2024, The Authors. All rights reserved.

关键词： Density functional theory

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Bosonic SET to SPT transition under dyonic LSM theorem

arXiv

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arXiv 2018年

作者： Wang, Yan-Cheng Yang, Xu Ran, Ying Meng, Zi Yang School of Physical Science and Technology China University of Mining and Technology Xuzhou221116 China Beijing National Laboratory for Condensed Matter Physics Institute of Physics Chinese Academy of Sciences Beijing100190 China Department of Physics Boston College Chestnut HillMA02467 United States CAS Center of Excellence in Topological Quantum Computation and School of Physical Sciences University of Chinese Academy of Sciences Beijing100190 China Songshan Lake Materials Laboratory Dongguan Guangdong523808 China

Employing large-scale quantum Monte Carlo simulatoins, we study the phase diagram of a quantum spin model which is subject to the recently developed dyonic Lieb-Shultz-Mattis (LSM) theorem. The theorem predicts there are symmetry enriched/protected topological (SET/SPT) phases in the phase diagram. Our numerical results reveal a first order quantum phase transition between SET and SPT phases, consistent with an anyon condensation mechanism that enforces SPT phase according to the theorem. Also there exists in the phase diagram a symmetry-breaking phase in the form of superfluid (SF). The transition between SET and SF is continuous and that between SPT and SF is first order. Interestingly, the SET, SPT and SF phases meet at a critical endpoint, whose presence can be universally explained via theory contains emergent gauge field coupled to vortex fields, and consequently reveals the exotic feature of our model even beyond the realm of dyonic LSM. Copyright © 2018, The Authors. All rights reserved.

关键词： Phase diagrams

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The leptonic di-flavor and di-number violation processes at high energy µ±µ± colliders

arXiv

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arXiv 2023年

作者： Yang, Jin-Lei Chang, Chao-Hsi Feng, Tai-Fu CAS Key Laboratory of Theoretical Physics Institute of Theoretical Physics Chinese Academy of Sciences Beijing100190 China School of Physical Sciences University of Chinese Academy of Sciences Beijing100049 China School of Physical Science and Technology Lanzhou University Lanzhou730000 China Department of Physics Hebei University Key Laboratory of High-precision Computation and Application of Quantum Field Theory of Hebei Province Baoding071002 China

The leptonic di-flavor violation (LFV) processes µ±µ± → e±e±, µ±µ± → τ±τ± and the leptonic di-number violation (LNV) processes µ±µ± ... 详细信息

The leptonic di-flavor violation (LFV) processes µ±µ± → e±e±, µ±µ± → τ±τ± and the leptonic di-number violation (LNV) processes µ±µ± → W±iW±j (i, j = 1, 2) at the same-sign high energy µ±µ± colliders are studied. The new physics (NP) factors that may play roles in these processes are highlighted by cataloging them into three types. Taking into account the experimental constraints, the processes at µ±µ± colliders are computed and the results are presented properly. The results lead to the conclusion that observing the NP factors through the LFV and LNV processes at TeVenergy µ±µ± colliders has significant advantages that cannot be achieved elsewhere. Therefore, in developing the techniques of muon acceleration and collisions, the option of building the same-sign muon high-energy colliders should be considered seriously too. © 2023, CC BY.

关键词： Charged particles

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Kπ scattering and the K*(892) resonance in 2+1 flavor QCD 36

Kπ scattering and the K*(892) resonance in 2+1 flavor QCD

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36th Annual International Symposium on Lattice Field Theory, LATTICE 2018

作者： Rendon, Gumaro Leskovec, Luka Meinel, Stefan Negele, John W. Paul, Srijit Petschlies, Marcus Pochinsky, Andrew Silvi, Giorgio Syritsyn, Sergey Department of Physics University of Arizona TucsonAZ85721 United States Computation-based Science and Technology Research Center Cyprus Institute Nicosia2121 Cyprus RIKEN BNL Research Center Brookhaven National Laboratory UptonNY11973 United States Center for Theoretical Physics Massachusetts Institute of Technology CambridgeMA02139 United States Department of Mathematics and Natural Sciences University of Wuppertal WuppertalD-42119 Germany Helmholtz-Institut für Strahlen- und Kernphysik University of Bonn BonnD-53115 Germany Department of Physics and Astronomy Stony Brook University Stony BrookNY11794 United States Forschungszentrum Jülich GmbH Jülich Supercomputing Centre Jülich52425 Germany

In this project, we will compute the form factors relevant for B → K∗(→ Kπ)`+`− decays. To map the finite-volume matrix elements computed on the lattice to the infinite-volume B → Kπ matrix elements, the Kπ scattering amplitude needs to be determined using Lüscher’s method. Here we present preliminary results from our calculations with 2 + 1 flavors of dynamical clover fermions. We extract the P-wave scattering phase shifts and determine the K∗ resonance mass and the K∗Kπ coupling for two different ensembles with pion masses of 317(2) and 178(2) MeV. © Copyright owned by the author(s) under the terms of the Creative Commons.

关键词： Lattice theory

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Study of decuplet baryon resonances from lattice QCD

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Physical Review D 2016年第11期93卷 114515-114515页

作者： C. Alexandrou J. W. Negele M. Petschlies A. V. Pochinsky S. N. Syritsyn Department of Physics University of Cyprus P.O. Box 20537 1678 Nicosia Cyprus Computation-based Science and Technology Research Center Cyprus Institute 20 Kavafi Street 2121 Nicosia Cyprus Center for Theoretical Physics Laboratory for Nuclear Science and Department of Physics Massachusetts Institute of Technology Cambridge Massachusetts 02139 USA Helmholtz-Institut fur Strahlen- und Kernphysik Rheinische Friedrich-Wilhelms-Universität Bonn Nußallee 14-16 D-53115 Bonn Germany RIKEN BNL Research Center Brookhaven National Laboratory Upton New York 11973 USA

A lattice QCD study of the strong decay width and coupling constant of decuplet baryons to an octet baryon-pion state is presented. The transfer matrix method is used to obtain the overlap of lattice states with decuplet baryon quantum numbers on the one hand and octet baryon-pion quantum numbers on the other as an approximation of the matrix element of the corresponding transition. By making use of leading-order effective field theory, the coupling constants as well as the widths for the various decay channels are determined. The transitions studied are Δ→πN, Σ*→Λπ, Σ*→Σπ and Ξ*→Ξπ. We obtain results for two ensembles of Nf=2+1 dynamical fermion configurations: one using domain wall valence quarks on a staggered sea at a pion mass of 350 MeV and a box size of 3.4 fm and a second one using domain wall sea and valence quarks at pion mass 180 MeV and box size 4.5 fm.

关键词： Hadronic decays Lattice QCD

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Enhancement of photoluminescence efficiency in GeSe ultrathin slab by thermal treatment and annealing: experiment and first-principles molecular dynamics simulations

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Scientific reports 2018年第1期8卷 17671页

作者： Yuliang Mao Xin Mao Hongquan Zhao Nandi Zhang Xuan Shi Jianmei Yuan Hunan Key Laboratory for Micro-Nano Energy Materials and Devices School of Physics and Optoelectronic Xiangtan University Hunan 411105 China. ylmao@***. Hunan Key Laboratory for Micro-Nano Energy Materials and Devices School of Physics and Optoelectronic Xiangtan University Hunan 411105 China. Chongqing institute of Green and Intelligent Technology Chinese Academy of Sciences Chongqing 401120 China. hqzhao@***. Chongqing institute of Green and Intelligent Technology Chinese Academy of Sciences Chongqing 401120 China. Hunan Key Laboratory for Computation and Simulation in Science and Engineering School of Mathematics and Computational Science Xiangtan University Hunan 411105 China.

The effect of thermal treatment and annealing under different temperatures from 100 °C to 250 °C on the photoluminescence spectroscopy of the GeSe ultrathin slab is reported. After the thermal treatment and annealing under 200 °C, we found that the photoluminescence intensity of A exciton and B exciton in GeSe ultrathin slab is increased to twice as much as that in untreated case, while is increased by ~84% in the photoluminescence intensity of C exciton. Combined by our experimental work and theoretical simulations, our study confirms the significant role of thermal treatments and annealing in reducing surface roughness and removing the Se vacancy to form more compact and smoother regions in GeSe ultrathin slab. Our findings imply that the improved quality of GeSe surface after thermal treatments is an important factor for the photoluminescence enhancement.

关键词： Thermal Treatment First-principles Molecular Dynamics Simulations Smoother Regions Reduced Surface Roughness GeSi Samples

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