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Quasinormal modes and isospectrality of Bardeen(Anti-)de Sitter black holes

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Chinese Physics C 2024年第3期48卷 191-202页

作者：赵莹刘文韬张超房熊俊荆继良 Department of Physics Key Laboratory of Low Dimensional Quantum Structures and Quantum Control of Ministry of Educationand Synergetic Innovation Center for Quantum Effects and ApplicationsInstitute of Interdisciplinary StudiesHunan Normal UniversityChangsha 410081China Department of Physics Faculty of ScienceTokyo University of Science1-3KagurazakaShinjuku-kuTokyo 162-8601Japan

Black holes(BHs)exhibiting coordinate singularities but lacking essential singularities throughout the spacetime are referred to as regular black holes(RBHs).The initial formulation of RBHs was presented by Bardeen,who considered the Einstein equation coupled with a nonlinear electromagnetic *** this study,we investigate the gravitational perturbations,including the axial and polar sectors,of the Bardeen(Anti-)de Sitter black *** derive the master equations with source terms for both axial and polar perturbations and subsequently compute the quasinormal modes(QNMs)through numerical *** the Bardeen de Sitter black hole,we employ the 6thorder WKB *** numerical results reveal that the isospectrality is broken in this ***,the QNM frequencies are calculated using the HH method for the Bardeen Anti-de Sitter black hole.

关键词： Bardeen quasinormal modes master equation

Highly efficient pH-universal hydrogen evolution reaction catalyzed by rapidly reconstructed bimetallic cobalt-molybdenum alloy cuboids arrays

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Nano Research 2024年第8期17卷 6977-6983页

作者： Daolian Liu Zihao Wang Yan Zhang Haiqing Zhou Yong Zhang Dongyang Li Fang Yu key laboratory of low-dimensional quantum structures and quantum control of ministry of education Key Laboratory for Matter Microstructure and Function of Hunan ProvinceDepartment of Physics and Synergetic Innovation Center for Quantum Effects and ApplicationsHunan Normal UniversityChangsha 410081China State key laboratory of Marine Resource Utilization in South China Sea and Department of Materials Science and EngineeringHainan UniversityHaikou 570228China Institute of Interdisciplinary Studies Hunan Normal UniversityChangsha 410081China

Given the inherent potential of seawater,industrial wastewater,and residential water as inherent feedstocks for hydrogen production through water electrolysis,there is a critical demand for the exploration of robust and stable hydrogen-evolving catalysts that can operate effectively across a diverse range of pH ***,the pursuit of hydrogen-evolving electrocatalysts that demonstrate both good stability and high efficiency over a wide pH range remains a formidable *** we report the rational design and synthesis of an outstanding nanoporous hybrid electrocatalyst consisting of intermetallic cobalt-molybdenum alloy particles anchoring on MoO2 cuboid arrays,which demands very low overpotentials of 72,123 and 134 mV to deliver a current density of−100 mA·cm^(−2)for hydrogen evolution reaction under alkaline,neutral and acidic conditions,*** catalytic activities are superior to most non-precious-metal-based catalysts documented in the literatures,and are even comparable to noble metal *** particular,this alloy electrocatalyst exhibits excellent stability at 50 or 300 mA·cm^(−2)without obvious activity degradation,which is further supported by the undetectable changes in the surface chemical valence states on the basis of in-situ X-ray photoelectron spectroscopic *** study provides an innovative strategy for the design and synthesis of effective non-noble intermetallic catalysts for pH-universal hydrogen evolution over a wide pH range.

关键词： electrocatalyst hydrogen evolution reaction pH-universal non-noble water splitting

Merger estimates for a disformal Kerr black hole in quadratic degenerate higher-order scalar-tensor theories

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Chinese Physics C 2024年第5期48卷 284-292页

作者：蒋洪鑫杜欣怡潘启沅陈松柏荆继良 key laboratory of low dimensional quantum structures and quantum control of ministry of education Synergetic Innovation Center for Quantum Effects and Applicationsand Department of PhysicsHunan Normal UniversityChangsha 410081China Institute of Interdisciplinary Studies Hunan Normal UniversityChangsha 410081China Center for Gravitation and Cosmology College of Physical Science and TechnologyYangzhou UniversityYangzhou 225009China

We investigate the main features of a disformal Kerr black hole merger in quadratic degenerate higher-order scalar-tensor *** the ringdown stage of the black hole merger,for the prograde orbit,the real part of the quasinormal modes decreases with an increase in the disformal parameter,and the imaginary part also decreases,except in the Kerr case for a large spin ***,for the retrograde orbit,the real part increases with an increase in the disformal parameter,and the imaginary part always decreases with *** the approximate final spin,regardless of an equal spin,unequal spin,or generic spin configuration merger,the final black hole spin always increases with an increase in the disformal *** results show that the disformal parameter in the disformal Kerr solution and the MOG parameter in the Kerr-MOG case have obviously different effects on the black hole merger,which suggests the differences between these two spacetime structures.

关键词： black hole merger quasinormal modes final black hole spin disformal Kerr black hole quadratic degenerate higher-order scalar-tensor(DHOST)theory

quantum squeezing induced nonreciprocal phonon laser

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Science China(Physics,Mechanics & Astronomy) 2024年第6期67卷 20-30页

作者： Tian-Xiang Lu Yan Wang keyu Xia Xing Xiao Le-Man Kuang Hui Jing College of Physics and Electronic Information Gannan Normal UniversityGanzhou 341000China key laboratory of low-dimensional quantum structures and quantum control of ministry of education Department of Physics and Synergetic Innovation Center for Quantum Effects and ApplicationsHunan Normal UniversityChangsha 410081China Academy for quantum Science and Technology Zhengzhou University of Light IndustryZhengzhou 450002China College of Engineering and Applied Sciences National Laboratory of Solid State Microstructuresand Collaborative Innovation Center of Advanced MicrostructuresNanjing UniversityNanjing 210023China

Phonon lasers or coherent amplifications of mechanical oscillations are powerful tools for fundamental studies on coherent acoustics and hold potential for diverse applications,ranging from ultrasensitive force sensing to phononic information ***,we propose the use of an optomechanical resonator coupled to a nonlinear optical resonator for directional phonon *** find that by pumping the nonlinear optical resonator,directional optical squeezing can occur along the pump *** a result,we can achieve the directional mechanical gain using directional optical squeezing,thereby leading to nonreciprocal phonon lasing with a well-tunable directional power *** work proposes a feasible way to build nonreciprocal phonon lasers with various nonlinear optical media,which are important for a wide range of applications,such as directional acoustic amplifiers,invisible sound sensing or imaging,and one-way phononic networks.

关键词： nonreciprocal phonon laser directional quantum squeezing optomechanics

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Energy flux and waveform of gravitational wave generated by coalescing slow-spinning binary system in effective one-body theory

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Science China(Physics,Mechanics & Astronomy) 2024年

作者： Weike Deng Sheng Long Jiliang Jing Department of Physics Key Laboratory of Low Dimensional Quantum Structures and Quantum Control of Ministry of Educationand Synergetic Innovation Center for Quantum Effects and Applications Hunan Normal University Center for Gravitation and Cosmology College of Physical Science and Technology Yangzhou University

We extend our research on the energy flux and waveform characteristics of gravitational waves generated by merging nonspinning binary black holes through self-consistent effective one-body theory to include binary systems with slowly spinning black ***, we decompose the equation for the null tetrad component of the gravitationally perturbed Weyl tensor ψB4into radial and angular parts, leveraging the second-order approximation of the rotation parameter a. Subsequently, we derive an analytical solution for the radial equation and observe that our results are contingent upon the parameters a2, a3, and a, which represent the second-and third-order correction parameters, respectively. Ultimately, we calculate the energy flux, the radiation-reaction force and the waveform for the “plus” and “cross” modes of the gravitational waves generated by merging slowly spinning binary black holes.

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High-resolution recognition of FOAM modes via an improved EfficientNet V2 based convolutional neural network

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Frontiers of physics 2024年第3期19卷 175-183页

作者： Youzhi Shi Zuhai Ma Hongyu Chen Yougang Ke Yu Chen Xinxing Zhou International Collaborative laboratory of 2D Materials for Optoelectronics Science and Technology Institute of Microscale OptoelectronicsShenzhen UniversityShenzhen 518060China key laboratory of low-dimensional quantum structures and quantum control of ministry of education Synergetic Innovation Center for Quantum Effects and ApplicationsSchool of Physics and ElectronicsHunan Normal UniversityChangsha 410081China key laboratory of Hunan Province on Information Photonics and Freespace Optical Communications School of Information Science and EngineeringHunan Institute of Science and TechnologyYueyang 414006China

Vortex beam with fractional orbital angular momentum (FOAM) is the excellent candidate for improving the capacity of free-space optical (FSO) communication system due to its infinite modes. Therefore, the recognition of FOAM modes with higher resolution is always of great concern. In this work, through an improved EfficientNetV2 based convolutional neural network (CNN), we experimentally achieve the implementation of the recognition of FOAM modes with a resolution as high as 0.001. To the best of our knowledge, it is the first time this high resolution has been achieved. Under the strong atmospheric turbulence (AT) (C_(n)^(2)=10^(-15)m^(-2/3)), the recognition accuracy of FOAM modes at 0.1 and 0.01 resolution with our model is up to 99.12% and 92.24% for a long transmission distance of 2000 m. Even for the resolution at 0.001, the recognition accuracy can still remain at 78.77%. This work provides an effective method for the recognition of FOAM modes, which may largely improve the channel capacity of the free-space optical communication.

关键词： OAM free-space optical communication deep learning convolutional neural network

Systematic study of cluster radioactivity within the generalized liquid drop model

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Chinese Physics C 2024年第6期48卷 118-129页

作者：邓军刚程俊皓包小军张鸿飞 College of Science China Three Gorges UniversityYichang 443002China Center for Astronomy and Space Sciences China Three Gorges UniversityYichang 443002China Department of Physics National University of Defense TechnologyChangsha 410073China Department of Physics Collaborative Innovation Center for Quantum Effectsand Key Laboratory of Low Dimensional Quantum Structures and Quantum Control of Ministry of EducationHunan Normal UniversityChangsha 410081China School of Physics Xi'an Jiaotong UniversityXi'an 710049China

Cluster radioactivity is studied within the generalized liquid drop model(GLDM),in which the shell correction energy,pairing energy,and cluster preformation factor are *** calculations show significant improvements and can reproduce the experimental data within a factor of 8.04 after considering these physical *** addition,the systematic trend of the cluster preformation factors is discussed in terms of the N_(p)N_(n)scheme to study the influence of the valence proton-neutron interaction and shell effect on cluster *** is found that log10Pcis linearly related to N_(p)N_(n).This is in agreement with a recent study[*** et al.,***.C 108,014325(2023)],in which log10Pc,obtained using different theoretical models and treatment methods than those used in this study,also had a linear relationship with N_(p)N_(n).Combined with the work by Qi et al.,this study suggests that the linear relationship between log10Pcand N_(p)N_(n)is model-independent and both the shell effect and valence proton-neutron interaction play essential roles in cluster *** analytical formula is proposed to calculate the cluster preformation factor based on the N_(p)N_(n)*** addition,the cluster preformation factors and the cluster radioactivity half-lives of some heavy nuclei are predicted,which can provide a reference for future experiments.

关键词： cluster radioactivity cluster preformation factor shell effect generalized liquid drop model

ARPES investigation of the electronic structure and its evolution in magnetic topological insulator MnBi2+2nTe4+3n family

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National Science Review 2024年第2期11卷 81-93页

作者： Runzhe Xu Lixuan Xu Zhongkai Liu Lexian Yang Yulin Chen State key laboratory of low dimensional quantum Physics Department of PhysicsTsinghua University School of Physical Science and Technology Shanghai Tech University and CAS-Shanghai Science Research Center Shanghai Tech laboratory for Topological Physics Frontier Science Center for quantum Information Collaborative Innovation Center of quantum Matter Department of Physics Clarendon LaboratoryUniversity of Oxford

In the past 5 years,there has been significant research interest in the intrinsic magnetic topological insulator family compounds MnBi2+2nTe4+3n（where n=0,1,2…）.In particular,exfoliated thin films of MnBi2Te4have led to numerous experimental breakthroughs,such as the quantum anomalous Hall effect,axion insulator phase and high-Chern number quantum Hall effect without Landau ***,despite extensive efforts,the energy gap of the topological surface states due to exchange magnetic coupling,which is a key feature of the characteristic band structure of the system,remains experimentally *** electronic structure measured by using angle-resolved photoemission （ARPES） shows significant deviation from ab initio prediction and scanning tunneling spectroscopy measurements,making it challenging to understand the transport results based on the electronic *** paper reviews the measurements of the band structure of MnBi2+2nTe4+3nmagnetic topological insulators using ARPES,focusing on the evolution of their electronic structures with temperature,surface and bulk doping and film *** aim of the review is to construct a unified picture of the electronic structure of MnBi2+2nTe4+3ncompounds and explore possible control of their topological properties.

关键词： magnetic topological insulator MnBi2Te4 electronic structure angle-resolved photoemission spectroscopy

Graphene binding on black phosphorus enables high on/off ratios and mobility

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National Science Review 2024年第2期11卷 188-195页

作者： Fanrong Lin Zhonghan Cao Feiping Xiao Jiawei Liu Jiabin Qiao Minmin Xue Zhili Hu Ying Liu Huan Lu Zhuhua Zhang Jens Martin Qingjun Tong Wanlin Guo Yanpeng Liu key laboratory for Intelligent Nano Materials and Devices of ministry of education State Key Laboratory of Mechanics and Control of Mechanical Structures and Institute for Frontier Science Nanjing University of Aeronautics and Astronautics Centre for Advanced 2D Materials National University of Singapore School of Physics and Electronics Hunan University Centre for quantum Physics Key Laboratory of Advanced Optoelectronic Quantum Architecture and MeasurementSchool of PhysicsBeijing Institute of Technology Leibniz Institute für Kristallzüchtung

Graphene is one of the most promising candidates for integrated circuits due to its robustness against short-channel effects, inherent high carrier mobility and desired gapless nature for Ohmic contact, but it is difficult to achieve satisfactory on/off ratios even at the expense of its carrier mobility, limiting its device applications. Here, we present a strategy to realize high back-gate switching ratios in a graphene monolayer with well-maintained high mobility by forming a vertical heterostructure with a black phosphorus multi-layer. By local current annealing, strain is introduced within an established area of the graphene, which forms a reflective interface with the rest of the strain-free area and thus generates a robust off-state via local current depletion. Applying a positive back-gate voltage to the heterostructure can keep the black phosphorus insulating, while a negative back-gate voltage changes the black phosphorus to be conductive because of hole accumulation. Then, a parallel channel is activated within the strain-free graphene area by edge-contacted electrodes, thereby largely inheriting the intrinsic carrier mobility of graphene in the on-state. As a result, the device can provide an on/off voltage ratio of >10～3 as well as a mobility of ～8000 cm2V-1s-1at room temperature, meeting the low-power criterion suggested by the International Roadmap for Devices and Systems.

关键词： graphene on/off ratio mobility black phosphorus reflective interface