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Statistical Entropy of the Kaluza-Klein Black Hole from the Horizon Conformal Field Theory

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Chinese physics Letters 2001年第3期18卷 331-333页

作者： JING Ji-Liang YAN Mu-Lin institute of physics and department of physics Hunan Normal UniversityChangsha 410081 department of astronomy and Applied physics University of Science and Technology of ChinaHefei 230026

The statistical entropy of the Kaluza-Klein black hole is studied by counting the black hole states which form an algebra of diffeomorphism at Killing horizon with a central *** is shown that the entropy yielded by the standard Cardy formula agrees with the Bekenstein-Hawking entropy only if we take period T of function u as the periodicity of the Euclidean black *** the other hand,the first-order quantum correction to the entropy is proportional to logarithm of the Bekenstein-Hawking entropy with a factor-1/2.

关键词： horizon periodicity entropy

Electronic correlation in nearly free electron metals with beyond-DFT methods

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npj Computational Materials 2022年第1期8卷 1756-1762页

作者： Subhasish Mandal Kristjan Haule Karin M.Rabe David Vanderbilt department of physics and astronomy West Virginia UniversityMorgantownWVUSA department of physics and astronomy Rutgers UniversityPiscatawayNJUSA

For more than three decades,nearly free-electron elemental metals have been a topic of debate because the computed bandwidths are significantly wider in the local density approximation to density-functional theory(DFT)than indicated by angle-resolved photoemission(ARPES)***,we systematically investigate this using first principles calculations for alkali and alkaline-earth metals using DFT and various beyond-DFT methods such as meta-GGA,G0W0,hybrid functionals(YS-PBE0,B3LYP),and LDA+*** find that the static non-local exchange,as partly included in the hybrid functionals,significantly increase the bandwidths even compared to LDA,while the G0W0 bands are only slightly narrower than in *** agreement with the ARPES is best when the local approximation to the self-energy is used in the LDA+eDMFT *** infer that even moderately correlated systems with partially occupied s orbitals,which were assumed to approximate the uniform electron gas,are very well described in terms of short-range dynamical correlations that are only local to an atom.

关键词： metals assumed narrow

Tunable non-Markovian and quantum coherence in the single-qubit dephasing noise channel

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Science China(physics,Mechanics & astronomy) 2025年

作者： Na-Na Zhang Chao-Yi Wu Xu Zhou Qi-Yuan Liu Cheng-Ge Liu Yong-Rui Guo Ren-Pu Li School of Optoelectronic Engineering Chongqing University of Posts and Telecommunications department of physics Applied Optics Beijing Area Major Laboratory Beijing Normal University

In this paper, we construct a single-qubit dephasing noise channel based on the nuclear magnetic resonance（NMR） system by employing the bath-engineering technology, and achieve the construction of the tunable non-Markovian environment in the dephasing noise channel. Our findings indicate that for the single-qubit system, the transition of system dynamics from Markovian to non-Markovian can be achieved by adjusting the base frequency of the noise power spectrum. However, the base frequency corresponding to this phase transition point is not fixed, and there is a certain relationship between it and the total evolution time of the single-qubit system. Through our research, we discovered a fundamental relationship: if the single-qubit system dynamics undergoe a transition from Markovian to non-Markovian at ω0within 0-2t ms, shortening the evolution time to 0-t ms results in an increase of the phase transition point to 2ω0. This insight offers crucial guidance for artificially crafting non-Markovian environments across arbitrary time scales in single-qubit systems, and it is not limited by the type of noise. Apart from system dynamics, quantum coherence is also a focal point of our research. We find that when the system dynamics exhibit non-Markovian behavior, the quantum coherence of the single-qubit system experiences revivals. Notably, the timing of these coherence revivals aligns with the instants of the non-Markovianity enhancement. Therefore, our research also serves as a pivotal foundation for the artificial manipulation and realization of quantum coherence revivals within diverse single-qubit systems.

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Thresholdless coherence in a superradiant laser

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Light(Science & Applications) 2024年第11期13卷 2549-2555页

作者： Seung-Hoon Oh Jinuk Kim Junseo Ha Gibeom Son Kyungwon An department of physics and astronomy&institute of Applied physics Seoul National UniversitySeoulKorea Korea Research institute of Standards and Science DaejeonKorea

Lasing threshold in the conventional lasers is the minimum input power required to initiate laser *** has been widely accepted that the conventional laser threshold occurring around a unity intracavity photon number can be eliminated in the input-output curve by making the so-calledβparameter approach *** recent experiments,however,have revealed that even in this case the photon statistics still undergo a transition from coherent to thermal statistics when the intracavity mean photon number is decreased below *** the coherent output is only available above the diminished threshold,the long-sought promise of thresholdless lasers to produce always coherent light has become ***,we present an always-coherent thresholdless laser based on superradiance by two-level atoms in a quantum superposition state with the same phase traversing a high-Q *** lasing was observed without the conventional lasing threshold around the unity photon number and the photon statistics remained near coherent even below *** coherence was improved by reducing the coupling constant as well as the excited-state amplitude in the superposition *** results pave a way toward always-coherent thresholdless lasers with more practical media such as quantum dots,nitrogen-vacancy centers and doped ions in crystals.

关键词： laser coherent lasing

What do parameterized Om(z) diagnostics tell us in light of recent observations?

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Research in astronomy and Astrophysics 2018年第6期18卷 49-58页

作者： Jing-Zhao Qi Shuo Cao Marek Biesiada Teng-Peng Xu Yan Wu Si-Xuan Zhang Zong-Hong Zhu department of astronomy Beijing Normal University department of Astrophysics and Cosmology Institute of Physics University of Silesia

In this paper, we propose a new parametrization for Om(z) diagnostics and show how the most recent and significantly improved observations concerning the H(z) and SN Ia measurements can be used to probe the consistency or tension between the ΛCDM model and observations. Our results demonstrate that H0 plays a very important role in the consistency test of ΛCDM with H(z)data. Adopting the Hubble constant priors from Planck 2013 and Riess, one finds considerable tension between the current H(z) data and ΛCDM model and confirms the conclusions obtained previously by others. However, with the Hubble constant prior taken from WMAP9, the discrepancy between H(z) data and ΛCDM disappears, i.e., the current H(z) observations still support the cosmological constant scenario. This conclusion is also supported by the results derived from the Joint Lightcurve Analysis(JLA) SN Ia sample. The best-fit Hubble constant from the combination of H(z)+JLA(H00 = 68.81+1.5-1.49 km s-1 Mpc-1) is very consistent with results derived both by Planck 2013 and WMAP9, but is significantly different from the recent local measurement by Riess.

关键词： cosmology: theory cosmology: observations cosmology: cosmological parameters

GTC Simulation of Ideal Ballooning Mode in Tokamak Plasmas

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Plasma Science and Technology 2013年第6期15卷 499-505页

作者：李泽彬孙国亚 Ihor HOLOD 肖湧张文禄林志宏 department of physics and institute of Theoretical physics and Astrophysics Xiamen University department of physics and astronomy University of CaliforniaIrvineCalifornia 92697USA institute of Fusion Theory and Simulation Zhejiang University CAS Key Laboratory of Basic Plasma physics University of Science and Technology of China department of physics and astronomy University of California Fusion Simulation Center Peking University

In the present paper,we first derive the eigenmode equation of the ideal ballooning mode in tokamak plasmas using a gyrokinetic *** is shown that the gyrokinetic eigenmode equation can be reduced to the magnetohydrodynamic（MHD） form in the long wavelength limit when kinetic effects are ***,the global gyrokinetic toroidal code（GTC） is applied for simulations of the edge-localized ideal ballooning *** obtained mode structures are compared with the results of ideal MHD *** observed scaling of the linear growth rate with the toroidal mode number is consistent with the ideal MHD *** simulation results verify the GTC capability of simulating MHD processes in toroidal plasmas.

关键词： edge-localized ideal ballooning mode global gyrokinetic toroidal code tokamak plasmas

Analyses of β-Bands of 230,232Th and 232,234U by the Projected Shell Model

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Chinese physics Letters 2012年第2期29卷 59-62页

作者： CUI Ji-Wei ZHOU Xian-Rong CHEN Fang-Qi SUN Yang WU Cheng-Li department of physics and institute of Theoretical physics and Astrophysics Xiamen UniversityXiamen 361005 department of physics and institute of nuclear particleastronomy and cosmologyShanghai Jiao Tong UniversityShanghai 200240

The ground bands and β-bands of four nuclei 230,232Th and 232,234U in the actinide region are investigated by introducing a collective Do pair into the projected shell *** discuss the collectivity of the Do *** calcu... 详细信息

关键词： bands collective model

Recent Developments on the H_(I)Gas of Low-Redshift Galaxies Seen by the 21 cm Emission Lines

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Chinese physics Letters 2024年第10期41卷 152-165页

作者： Jing Wang Xuchen Lin Kavli institute for astronomy and Astrophysics Peking UniversityBeijing 100871China department of astronomy School of PhysicsPeking UniversityBeijing 100871China

As a major interstellar medium,the atomic neutral hydrogen(H_(I))plays an important role in the galaxy *** provides the ingredient for star formation,and sensitively traces the internal processes and external perturbations influencing the *** the beginning of many new radio telescopes and surveys,H_(I)may make a more significant contribution to the understanding of galaxies in the near *** review discusses the major development of the 21 cm emission-line H_(I)observations and studies in the past few years,including its scaling relations with other galaxy properties,its kinematics and structures,its role in environmental studies,and its constraints on hydrodynamical *** local-Universe H_(I)scaling relations of stellar-massselected samples extend smoothly to 10^(9)M⊙stellar mass,with a tentative evolution to the redshift of∼*** development of measurement techniques enables better estimations of H_(I)non-circular motion,dispersion,and thickness,and new observations revealed extended or extra-planar H_(I)structures,both helpfully constraining the gas accretion,stellar feedback,and star formation processes of galaxy evolution models.H_(I)is very useful for tracing the satellite evolution in dense environments,the studies of which would benefit from ongoing blind H_(I)*** simulations still cannot fully reproduce H_(I)gas properties,they help to understand the role of possible factors in regulating H_(I)properties.

关键词： evolution. galaxy stellar

The physics of spin rectification and its application

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Science China(physics,Mechanics & astronomy) 2013年第1期56卷 124-141页

作者： GUI YongSheng BAI LiHui HU CanMing department of physics and astronomy University of Manitoba

A coherent nonlinear coupling between the charge and spin dynamics of electrons results in the rectification of microwaves,which is enhanced through resonant magnetization dynamics such as ferromagnetic *** property,known as the spin rectification effect,enables the spin dynamics within a material to be electrically detected with a high *** utilizing this property have been widely used to study the magnetization dynamics of various ferromagnetic materials and structures in the past ***,the coherent nature of spin rectification opens the door for spintronic devices to be used in phase-resolved microwave sensing *** this work we review the physics of spin rectification and its applications in several interesting topics of magnetism and spintronics.

关键词： spintronics ferromagnetic resonance spin waves nonlinear ferromagnetic resonance nondestructive testing of materials