利用原子腔场的Raman相互作用制备多种形式的原子纠缠态

提出了一种利用Λ型三能级原子与相干态腔场的Raman相互作用制备原子纠缠态的方案.研究表明,在简单的条件下,可获得多种形式的原子纠缠态 关键词：     

利用原子与光场的非最大纠缠态传送薛定谔猫态

利用二能级原子与腔场的共振相互作用Jaynes-Cummings(J-C)模型，制备出原子与光场的纠缠态，通过改变相互作用时间，可以控制纠缠态的纠缠程度。提出了利用这个原子与光场的非最大纠缠态，通过大失谐的J-C模型传送腔场的薛定谔猫态的方案。     

基于腔QED的原子纠缠态的辅助克隆

本文提出一种克隆未知两原子纠缠态的方案，这种克隆方案基于腔QED技术，且在原子态制备态（Victor）的帮助下而完成。方案包括了两个步骤：第一步需要用通常的隐形传态方法，运用腔QED技术及纠缠交换实现原子纠缠态从发送者（Alice）到接收者（Bob）的隐形传送；第二步是由Victor完成来之于Alice的两原子态的离散测量，根据Victor的测量信息，Alice能够获得未知初始原子纠缠态的拷贝。     

Tavis-Cummings模型中原子运动时三体纠缠量的演化特性

用全量子理论研究了原子运动时两纠缠二能级原子与单模真空场相互作用体系的纠缠特性.研究结果表明:当双原子初始处在EPR态时,三体纠缠量最大值与理想W纠缠态纠缠量相同.场模结构参数p影响三体纠缠量随时间演化的振荡特性,随着p值的逐渐增大,三体纠缠量的平均值将越来越小,体系三体纠缠态也会逐渐趋于消纠缠状态.     

W类态三纠缠原子与相干态光场相互作用过程中光场的量子特性

研究了处于W类态的三纠缠原子与相干态光场相互作用过程中光场的量子特性;运用数值方法,讨论了三纠缠原子初始状态和相干态光场的强弱对系统光场压缩和二阶相干特性的影响。     

两纠缠原子与二项式光场相互作用的动力学

采用时间演化算符和数值计算方法，研究了两全同二能级纠缠原子与二项式光场相互作用的动力学，结果表明原子布居和原子偶极压缩的时间演化与二项式光场系数和两纠缠原子的纠缠度有很强的关联，选择合适的系统参数，原子偶极矩可以被完全压缩. 关键词： 纠缠原子 二项式态 原子布居 偶极压缩     

两纠缠原子与相干态光场相互作用的动力学

采用时间演化算符和数值计算方法,研究了两全同二能级纠缠原子与相干态光场相互作用的动力学,结果表明:原子布居和偶极压缩特性与两原子体系纠缠度和相干态光场强度相关联.     

W态纠缠实现双腔远程控制原子的非经典特性

考虑将双模纠缠相干光场的两模场同时分别注入两个腔中,初态处于W态的三体纠缠二能级原子中的两个分别在这两个腔内,并且都与光场发生共振相互作用,经腔QED演化之后,对纠缠相干光场进行光子探测和对纠缠原子进行选择性测量,通过操纵相互作用的时间和光场的参数可控制W态中处于腔外的第三个原子的非经典效应,如粒子数布居差的崩塌一回复现象和偶极压缩现象,从而实现了更强地远程控制原子的非经典特性.     

多光子Tavis-Cummings模型中两纠缠原子的纠缠演化特性

研究了两个纠缠的二能级原子通过多光子跃迁与单模相干光场进行耦合相互作用系统中两原子纠缠的演化特性.计算分析表明,两个原子之间的纠缠呈现出周期性的演化特性,初始两原子的状态、原子间的偶极相互作用、相干光场的参数以及跃迁光子数对两个原子的纠缠有着显著的影响;并发现两原子初始处于某最大纠缠态时,两原子会永远处于该最大纠缠态,因此这一类最大纠缠态可以作为一种量子信息存储器. 关键词： 量子纠缠 部分转置矩阵负本征值 纠缠原子 相干态     

远程制备双原子纠缠态

提出一种远程制备双原子纠缠态的方案,该方案基于两个原子与单模腔场的同时非共振相互作用.由于双粒子纠缠态比三粒子纠缠态容易制备,方案用两对双原子纠缠态作为量子通道.Alice 拥有的两个相同原子同时与一单模腔场非共振相互作用.Alice已知她要制备的纠缠态,她选择适当的相互作用时间、测量她所拥有的两个原子并通过经典通道通知Bob.Bob引入一个相同的辅助原子和一个单模腔场来实现方案.方案对腔场状态和腔损耗不敏感,基于当前的腔QED 技术,方案能在实验上实现.该方案有望在量子信息过程中有重要的应用价值.     

Entanglement and Pancharatnam Phase for Two Two-Level Atoms Interacting with a Single Mode Field

A model of two 2-level atoms interacts with a single quantized electromagnetic field is considered. We study the effect of the mean photon number and the structure of the initial states of the two atoms on the dynamics of the atomic system from the separability point of view. It is found that, if we start from a product mixed atomic state, the probability of generating long living entangled states is increased as the mean photon number increases. Starting from excited atomic system in product state, one generates a more stable entangled states with high degree of entanglement. Also, the effect of the mean photon number on atomic system prepared initially in entangled states is investigated. It is found that the entangled state generated from the initially partial entangled states are more robust than those obtained from a maximum entangled state. The Pancharatnam phase for the separable and entangled states is studied under the effect of the mean photon number and the structure of the initial state. We find that for the separable states, the collapses decrease and the amplitude of the revivals is smaller than that for the entangled state, so there are long-living entangled phases. This property give us a great chances to store safely information in entangled state.     

Quantum Nondemolition Measurement of Entangled Atomic Ensembles in Coupled Cavity System

Quantum nondemolition measurement scheme for entangled atomic ensembles was presented when they are restricted in two distant coupled cavities. Under certain conditions, we showed that the entanglement evolution of both the atomic ensembles and cavity fields are of the same periods, which provides us with potential nondemolitionmeasurement of entangled atomic ensembles by experimentally detecting cavity fields. Including the dissipation of the cavity fields, the same steps of evolution still hold. Furthermore, it is shown that we can have the two-mode squeezing steady-states of both the cavity fields and the atomic ensembles, which really provides us with the quantum nondemolition measurement of the entangled atomic state.     

纠缠相干态光场驱动下∧-型三能级原子的辐射谱

采用时间演化算符方法,研究∧-型=三能级原子与纠缠相干态光场共振相互作用的辐射谱.给出了辐射谱一般公式,并讨论在纠缠相干态光场驱动下的辐射频谱结构.结果表明,无论下能级简并与否纠缠相干态光场平均光子数很小时均出现拉比分裂,且强度随双模光场纠缠程度的增加而增加.当两下能级简并时,若两模场的平均光子数较小,辐射谱呈现对称多峰结构,若两模场的平均光子数较大,辐射谱呈现对称五峰结构.当两下能级非简并时,若两模场的平均光子数较小,辐射谱呈现对称多峰结构.若两模场的平均光子数较大,辐射谱呈现对称十峰结构.纠缠相干光与非纠缠相干光辐射谱的本质差别有两点:一是双模光场强量子关联导致纠缠度越强拉比峰强度越高;二是存在纠缠时由于两模场相干性导致辐射谱呈现对称多峰结构.     

二能级原子与相干态腔场相互作用过程中的纠缠交换

用量子信息学的观点，分析了发生在一个多个原子和腔场组成的系统中最大纠缠态在原子和多模类奇-偶相干态光场之间相互转移的物理过程，该系统中原子和腔场之间由依赖于强 度耦合的Jaynes-Cummings模型描述.结果发现：通过控制原子与腔场相互作用的时间，并 对原子的状态进行测量，原子的最大纠缠态可以转换为类奇-偶相干态光场的最大纠缠态，反之，纠缠的多模类奇-偶相干态光场也可以转换为原子的最大纠缠态. 关键词： 量子信息 腔量子电动力学 连续变量纠缠态 纠缠交换和传递     

Preparation and control of entangled states in the two-mode coherent fields interacting with a moving atom via two-photon process

We investigate the preparation and the control of entangled states in a system with the two-mode coherent fields interacting with a moving two-level atom via the two-photon transition. We discuss entanglement properties between the two-mode coherent fields and a moving two-level atom by using the quantum reduced entropy, and those between the two-mode coherent fields by using the quantum relative entropy. In addition, we examine the influences of the atomic motion and field-mode structure parameter $p$ on the quantum entanglement of the system. Our results show that the period and the duration of the prepared maximal atom-field entangled states and the frequency of maximal two-mode field entangled states can be controlled, and that a sustained entangled state of the two-mode field, which is independent of atomic motion and the evolution time, can be obtained, by choosing appropriately the parameters of atomic motion, field-mode structure, initial state and interaction time of the system.     

Generation of Entangled Bloch States for Two Atomic Samples Trapped in Separated Cavities

A scheme is presented for the cavities. In the scheme, each a coherent state with a small generation of entangled states for two atomic ensembles trapped in two distant atomic sample is initially in a Bloch state and the cavity mode is initially in amplitude. The dispersive dependent phase shift on the atomic system. The detection atomic samples collapse to an entangled Bloch state. atom-cavity interaction leads to a photon-number of a photon leaking from the cavities makes the two     

Squeezing and entanglemëent of atomic beams

We propose and analyze a scheme for generating entangled atomic beams out of a Bose-Einstein condensate using spin-exchanging collisions. In particular, we show how to create both atomic squeezed states and entangled states of pairs of atoms.     

Concentration of Unknown Atomic Entangled States via Entanglement Swapping through Raman Interaction

We show that entanglement concentration of unknown atomic entangled states is achieved via the implementation of entanglement swapping based on Raman interaction in cavity QED. A maximally entangled state is obtained from a pair of partially entangled states probabilistically. Due to Raman interaction of two atoms with a cavity mode and an external driving field, the influence of atomic spontaneous emission has been eliminated. Because of the virtual excitation of the cavity mode, the decoherence of cavity decay and thermal field is neglected.     

双模纠缠相干光场与V型三能级原子相互作用系统的原子偶极压缩效应

采用求解Schroedinger方程和数值计算方法，研究了双模纠缠相干光场与V型三能级原子相互作用过程中原子偶极算符的压缩效应，结果表明：此压缩效应与双模纠缠光场的纠缠程度、失谐量相关联。     

GENERATION OF ENTANGLED FOCK STATES OF TWO NONLOCAL CAVITY MODES WITH DIFFERENT FREQUENCIES

We present a method to generate entangled Fock states of two nonlocal cavity modes with different frequencies. We send an atom with three levels g,e, and f across two cavities. The atomic transition frequency between level g and e is resonant with the first cavity frequency, while the atomic transition frequency between level g and f is resonant with the second cavity frequency. The detection of the atomic state leaves the pure field in an entangled Fock state.