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Spin Transport Properties of the One-Dimensional Heisenberg Chain： Bethe-Ansatz Solution with Twist Boundary Conditions

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Chinese Physics Letters 2007年第5期24卷 1354-1356页

作者：张秋兰顾世建 Department of Physics and ITP The Chinese University of Hong Kong Hong Kong Zhejiang Institute of Modern Physics Zhejiang University Hangzhou 310027

Based on the Bethe-Ansatz solution of the one-dimensional Heisenberg model under twist boundary conditions, we study the spectra of the persistent current carried by the low-lying excited states. It is shown that though the energy spectra of spin-singlet and spin-triplet excitations are degenerate, their persistent current spectra are quite different.

关键词： HUBBARD RINGS MODEL SR2CUO3

Maximizing Thermal Entanglement of XY Model Using Site-Dependent Magnetic Fields in Specific Directions

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Chinese Physics Letters 2008年第3期25卷 832-835页

作者：陈文岭杨东顾世建 Department of Physics and ITP The Chinese University of Hong Kong Hong Kong Laboratory for Quantum Information and Department of Physics China Jiliang University Hangzhou 310018

We study the thermal entanglement by means of concurrence in a two-qubit isotropic XY model in the presence of site-dependent external magnetic fields in arbitrary directions. We find that at a given temperature and magnetic field strength, the mirror symmetry of the two fields about the x-y plane is a necessary condition for maximum entanglement. However, if there is no constraint on the field strengths, then the necessary condition for maximum entanglement reduces to the configuration that the two fields are vertical, anti-parallel and with the same strength. We also investigate the anisotropic XY model and find that the above conclusion more or less holds.

关键词： supernova explosion proto-neutron star shock wave

Fermionic Concurrence in the Extended Hubbard Model

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Chinese Physics Letters 2005年第4期22卷 804-807页

作者：邓蜀萨顾世建 DepartmentofPhysics TheChineseUniversityofHongKongHongKong

We study the fermionic concurrence in an extended Hubbard model. Itsbehaviour at the ground state and at finite temperatures for general U and V is obtained numericallyand analytically for a dimer system. We also investigate the properties of the concurrence under anonuniform field, and we End that it can be used to modulate and to increase the concurrence.

关键词： ENTANGLEMENT

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q类|α,p〉态的压缩及振幅平方压缩性质

量子电子学报 1998年第3期15卷 273-278页

作者：蔡寿福顾世建李楚良浙江近代物理中心浙江大学物理系杭州310027

在引入q形变技术的基础上，我们研究了q形变相干态的一些压缩性质。研究发现，压缩性质不但与｜α，q〉态中的相因子ψ及θ密切相关，还与q因子有关。r的增加，会增强态的压缩性。通过数值计算，给出了最大压缩度下的r值。

关键词： q形变压缩性振幅平方压缩量子力学

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由杂质自旋散射引起的纠缠

大学物理 2011年第6期30卷 4-7页

作者：尤文龙顾世建苏州大学物理科学与技术学院江苏苏州215006 香港中文大学物理系

研究了自由电子与固定杂质自旋的散射过程中的纠缠行为.研究发现,固定自旋的杂质能起到纠缠过滤器的作用,实现自由电子间的纠缠浓缩.当两无相互作用的电子先后经过同一Kondo杂质并与之发生散射时,可以使得原本不纠缠的电子发生纠缠.类似... 详细信息

研究了自由电子与固定杂质自旋的散射过程中的纠缠行为.研究发现,固定自旋的杂质能起到纠缠过滤器的作用,实现自由电子间的纠缠浓缩.当两无相互作用的电子先后经过同一Kondo杂质并与之发生散射时,可以使得原本不纠缠的电子发生纠缠.类似地,当运动的电子先后经过两无相互作用的Kondo杂质并与它们发生散射,可以使得原本不纠缠的Kondo杂质产生纠缠,从而实现了纠缠的生成.

关键词：纠缠散射自由电子 Kondo杂质

Pairwise Entanglement and Quantum Phase Transitions in Spin Systems

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Chinese Physics Letters 2007年第10期24卷 2737-2740页

作者：顾世建田光善林海青 Department of Physics and Institute of Theoretical Physics The Chinese University of Hong Kong Hong Kong School of Physics Peking University Beijing 100871

We examine several well-known quantum spin models and categorize the behaviour of pairwise entanglement at quantum phase transitions. A unitied picture on the connection between the entanglement and quantum phase tran... 详细信息

关键词： CHAIN

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保真率与量子相变

物理 2010年第3期39卷 157-161页

作者：顾世建林海青香港中文大学物理系

量子相变是量子多体理论中的一个重要概念,保真度则是量子信息学的重要概念.文章简单介绍了一个量子系统的基态对系统参量的响应,即保真率,在量子相变中的行为.作为理解量子相变的一个新的视角,保真度方法的优势在于它是一个纯粹的几何... 详细信息

量子相变是量子多体理论中的一个重要概念,保真度则是量子信息学的重要概念.文章简单介绍了一个量子系统的基态对系统参量的响应,即保真率,在量子相变中的行为.作为理解量子相变的一个新的视角,保真度方法的优势在于它是一个纯粹的几何学量,所以在研究相变过程中不需要考虑任何预设的序参量.文章用通俗的语言介绍了基态保真度、保真率、量子绝热维度以及它们的物理意义.为便于理解,文章以Lipkin-Meshkov-Glick模型与Kitaev蜂巢模型为例,对保真率在这两个模型中的性质做了简单介绍.

关键词：保真率量子相变

Competitions of magnetism and superconductivity in FeAs-based materials

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Chinese Physics B 2009年第6期18卷 2545-2550页

作者：杨硕尤文龙顾世建林海青 Department of Physics and ITP The Chinese University of Hong Kong Institute of Theoretical Physics Chinese Academy of Sciences

Using the numerical unrestricted Hartree-Fock approach, we study the ground state of a two-orbital model describing newly discovered FeAs-based superconductors. We observe the competition of a （0, π） mode spin-density wave and the superconductivity as the doping concentration changes. side where the magnetism and superconductivity coexist. The orbital even, and coexisting sxy ＋dx^2-y^2 wave （even parity）. There might be a small region in the electron-doping superconducting pairing is found to be spin singlet,

关键词： FeAs-based superconductors magnetism Hartree-Fock approach pairing symmetry

Repeater-Assisted Zeno Effect in Classical Stochastic Processes

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Chinese Physics Letters 2012年第1期29卷 17-19页

作者： GU Shi-Jian WANG Li-Gang WANG Zhi-Guo LIN Hai-Qing Department of Physics and ITP The Chinese University of Hong KongHong Kong Department of Physics Zhejiang UniversityHangzhou 310027 Department of Physics Tongji UniversityShanghai 200092

We address the possibility of the classical Zeno effect in classical stochastic processes as sampled by transferring a digitized image through a classical channel with surrounding *** is shown that the the classical state of the image decays inevitably with the distance of the channel due to the interference of the ***,if there are enough repeaters,which can both check and recover the state’s information,the classical state’s decay rate will be significantly suppressed,then a classical Zeno effect might occur.

关键词： decay stochastic digit