玻色-爱因斯坦凝聚体自囚禁现象的动力学相变及其量子纠缠特性

研究了量子涨落对自囚禁现象的影响.采用玻色-爱因斯坦凝聚体(BEC)两模模型进行研究，发现有限粒子BEC系统自囚禁现象的发生同样存在临界现象，但是由于量子涨落的影响使得这个临界现象变得模糊，并且粒子数越小量子涨落的影响越明显.为了更加明确地描述有限粒子系统的自囚禁现象，通过系统各态平均占有概率的熵(简称平均熵)和平均纠缠熵来刻画自囚禁现象，并讨论自囚禁现象发生前后系统的纠缠特性. 关键词： 玻色-爱因斯坦凝聚(BEC) 自囚禁 纠缠熵     

虚光场对双模SU(1,1)相干态光场与原子玻色-爱因斯坦凝聚体相互作用系统中量子纠缠的影响

在双模SU(1,1)相干态光场和原子玻色-爱因斯坦凝聚体相互作用系统中, 应用全量子理论, 在非旋波近似下, 分别利用量子约化熵和量子相对熵, 研究了双模SU(1,1)相干态光场与原子玻色-爱因斯坦凝聚体间的量子纠缠和双模光场的模间纠缠, 讨论了虚光场、原子-场的耦合常数和光场参数对场-凝聚体原子纠缠和光场模间纠缠的影响.     

V型三能级原子玻色-爱因斯坦凝聚体与双模压缩光场相互作用系统中光场的量子相关性质

研究了V型三能级原子的玻色-爱因斯坦凝聚体(BEC)与双模压缩态光场相互作用系统中光场的量子相关特性。结果表明：双模压缩态光场在与原子玻色-爱因斯坦相互作用过程中，其量子相关性质保持不变，完全决定于初始光场。     

光场-原子BEC相互作用系统的量子相关性质

运用全量子理论,在Bogoliubov近似下研究了光场与二能级原子玻色-爱因斯坦凝聚体(BEC)相互作用系统的量子相关性质,结果表明:光场和原子玻色-爱因斯坦凝聚体在相互作用过程中,其量子相关性质保持不变.     

SU(1,1)相干态与玻色-爱因斯坦凝聚相互作用系统中的量子纠缠

研究的系统为SU(1, 1)相干态和玻色-爱因斯坦凝聚体相互作用体系,在双光子跃迁过程中,分别用量子约化熵和量子相对熵研究了该系统中的SU(1, 1)相干态与凝聚体间的纠缠以及SU(1, 1)相干态的模间纠缠,分析了光场初始压缩因子、原子间相互作用对场-凝聚体间纠缠和模间纠缠的影响。     

SU(1,1)相干态与玻色-爱因斯坦凝聚相互作用系统中的量子纠缠

研究的系统为SU(1, 1)相干态和玻色-爱因斯坦凝聚体相互作用体系,在双光子跃迁过程中,分别用量子约化熵和量子相对熵研究了该系统中的SU(1, 1)相干态与凝聚体间的纠缠以及SU(1, 1)相干态的模间纠缠,分析了光场初始压缩因子、原子间相互作用对场-凝聚体间纠缠和模间纠缠的影响。     

原子间相互作用对光场和原子激光压缩性质的影响

对文献中给出的光场与二能级原子玻色-爱因斯坦凝聚体(BEC)相互作用系统的哈密顿量进行分析，表明文献中对原子间相互作用部分的处理有不合理之处，文献中的处理过高估计了原子间相互作用的贡献，从而对该哈密顿量作出了改进.用改进的哈密顿量解析地求解了非旋波近似下光子和原子算符的运动方程，并结合BEC的有关实验条件对哈密顿量中的有关参数作出了估计，研究了光场与原子玻色-爱因斯坦凝聚体相互作用系统中，光场和耦合输出相干原子束的压缩性质.结果表明：光场两正交分量的涨落均随时间按余弦规律周期性地变化，原子激光的两正交分量 关键词： 玻色-爱因斯坦凝聚 压缩相干态 光场的正交压缩 压缩原子激光     

相互作用原子玻色-爱因斯坦凝聚体诱导的光场压缩效应

给出了光场与二能级原子玻色-爱因斯坦凝聚体(BEC)相互作用系统的哈密顿量，研究了原子 间相互作用对压缩相干态光场与原子BEC相互作用系统中光场正交压缩特性的影响.结果表明 ：光场两正交分量的涨落均随时间按余弦规律周期性地变化，其压缩性质依赖于光场的初始 压缩因子和压缩方向角，而原子间的相互作用影响光场正交分量的涨落随时间变化的幅度和 周期. 关键词： 玻色-爱因斯坦凝聚 压缩相干态 光场的正交压缩     

具有纠缠序参量的玻色-爱因斯坦凝聚体

对最近提出的具有纠缠序参量的玻色-爱因斯坦凝聚体作通俗简要的介绍．在这个凝聚体中，不同种原子间形成自旋纠缠的原子对，而系统就在这个纠缠对上发生玻色-爱因斯坦凝聚.     

稀薄原子气体玻色-爱因斯坦凝聚近期研究进展简介

论述了自1999年涡旋态在稀薄碱金属原子气体的玻色-爱因斯坦凝聚体(BEC)中成功实现以来有关的BEC理论和实验研究的进展及作近期的部分探索，并介绍了相关的基本概念和理论。     

Dynamic Behavior of Lambda-Type Three-Level Atoms and Two-Mode Cavity Field

A system comprising of Lambda-type three-level atoms and the two-mode cavity field is considered in this paper. Under the adiabatical approximation and the large detuning condition, the effective Hamiltonian of the system in the interaction picture can be given out. If the two identical three-level atoms pass through the cavity in turn, the entangled state atoms can be generated. When the interaction time is taken to an appropriate value, the maximally entangled states are created. At the same time, the dynamic behaviors of the system are studied in detail.     

Quantum Information Splitting of an Arbitrary Three-Qubit State Via a Seven-Qubit Maximally Entangled State

Recently Zha et al. (J. Phys. A: Math. Theor. 45:255–302 2012) have proposed a seven-particle maximally entangled state. In this paperwe propose a schemes for splitting three-qubit states by using seven-particle maximally entangled state as the quantum channel. After the sender performs Bell-basis measurements on her particles, and the cooperators operate single-particle measurements on their particles, the state receiver can reconstruct the original state of the sender by applying the appropriate unitary operation.     

Scheme for realizing entanglement concentration via generalized measurements

How to concentrate non-maximally entangled states for quantum communication is a fundamental problem in quantum information. In this paper, we will apply generalized measurements to entanglement concentration of known non-maximally entangled pure states in arbitrary dimensional system. How to design the generalized measurements for the unambiguous discrimination of linearly independent non-orthogonal states is crucial for the concentration of the known non-maximally entangled states. The result shows that, any known non-maximally entangled pure state (for arbitrary dimensional system) can be transformed to the maximally entangled state only by introducing a qubit as ancilla and a joint unitary transformation operation on one of the entangled particles and the ancilla. In addition, because the less entangled state of each fail round will be re-concentrated too, the entanglement waste during the concentration process will be greatly reduced.     

Quantum teleportation of an Einstein-Podolsy-Rosen pair using an entangled three-particle state

Quantum teleportation of an Einstein-Podolsky-Rosen pair using maximally entangled triplets to two receivers is studied. The projection basis for combined three-particle measurements, from the results of which the unknown state can be reconstructed, is found. The basis contains states where only two of the three particles are maximally entangled.     

基于腔QED制备W纠缠态

利用一个三能级原子与四个腔场之间相互作用研究双光子四粒子体系W态的制备,通过合适选择原子与腔场之间的相互作用时间可以获得该态的最大保真度以及成功几率     

A Scheme of Controlled Quantum State Swapping

A scheme for controlled quantum state swapping is presented using maximally entangled five-qubit state,i.e.,Alice wants to transmit an entangled state of particle a to Bob and at the same time Bob wants to transmit an entangled state of particle b to Alice via the control of the supervisor Charlie.The operations used in this swapping process including C-not operation and a series of single-qubit measurements performed by Alice,Bob,and Charlie.     

A Scheme of Controlled Quantum State Swapping

A scheme for controlled quantum state swapping is presented using maximally entangled five-qubit state, i.e., Alice wants to transmit an entangled state of particle a to Bob and at the same time Bob wants to transmit an entangled state of particle b to Alice via the control of the supervisor Charlie. The operations used in this swapping process including C-not operation and a series of single-qubit measurements performed by Alice, Bob, and Charlie.     

3对非最大纠缠粒子的确定性纠缠浓缩协议

在Nielsen定理和纠缠浓缩基本思想的基础上,对从2对非最大纠缠粒子中提取1对最大纠缠粒子的确定性纠缠浓缩协议进行了简化和改进,从而建立了一个从3对非最大纠缠粒子中提取2对最大纠缠粒子的确定性纠缠浓缩协议.该协议利用经典通信和局域操作并通过特定的正算符测度来实现,避免了概率性的风险.这有助于n对非最大纠缠粒子中提取k对最大纠缠粒子的确定性纠缠浓缩协议的最终确立.     

Quantum Teleportation of the Two-Qubit Entangled State by Use of Four-Qubit Entangled State

In this article, a scheme for quantum teleportation of a two-qubit entangled state using four-qubit cluster state is discussed by use of cavity quantum electrodynamics (QED) involving the interaction of the atoms with the cavity. In this protocol, by using a one-dimensional maximally four-qubit cluster state as quantum channel, quantum information of an unknown state of two two-level particles is faithfully transmitted from a sender (Alice) to a remote receiver (Bob). According to the results measured by the Bob, as it is shown, the unknown two-particle entangled state can be teleported perfectly, and the successful possibilities and fidelities of the scheme can reach 1.0.     

Effects of three-body interactions on the dynamics of entanglement in spin chains

With the consideration of three-body interaction, dynamics of pairwise entanglement in spin chains is studied. The dependence of pairwise entanglement dynamics on the type of coupling, and distance between the spins is analyzed in a finite chain for different initial states. It is found that, for an Ising chain, three-body interactions are not in favor of preparing entanglement between the nearest neighbor spins, while three-body interactions are favorable for creating entanglement between remote spins from a separable initial state. For an isotropic Heisenberg chain, the pairwise concurrence will decrease when three-body interactions are considered both for a separable initial state and for a maximally entangled initial state, however, three-body interactions will retard the decay of the concurrence in an Ising chain when the initial state takes the maximally entangled state.