通过Raman相互作用制备三个腔场的W型纠缠相干态

通过对比分立变量量子信息过程和连续变量量子信息过程的差别,利用相干态比较容易获得的这个特点,提出一种方案制备三个腔场的W型纠缠相干态.方案基于Λ型三能级原子与单模腔场的简并Raman 相互作用.三个相同的腔初始分别处于相干态,三个相同的原子初始处于W型纠缠态,通过三个原子分别与三个腔的Raman相互作用、选择适当的相互作用时间并探测作用后的三个原子,三个腔场坍缩为W型纠缠相干态.在原子与腔的相互作用过程中原子不处于高能级,可以忽略原子的自发辐射,系统的相干性能够得到较好的维持.基于当前的腔量子电动力学技术,相信方案能在实验上实现.该方案制备的三个腔场W型纠缠相干态有望在连续变量量子信息过程中有重要的应用价值.文中将方案推广到制备n(n〉3)个腔场的W型纠缠相干态.     

可控制权重因子的原子纠缠态的制备

提出了一种利用二能原子与相干态腔场的非共振相互作用制备原子纠缠态的方案。在一定条件下,获得了可控制权重因子的原子纠缠态以及纠缠两原子的4个贝尔基。     

利用原子-腔场的Raman相互作用制备类自旋多腔场纠缠态

提出了一种利用Λ型三能级原子与相干态腔场的Raman相互作用制备类自旋多腔场纠缠态的方案.     

利用Raman相互作用实现未知原子态的传输

利用Λ型三能级原子与单模腔场之间的相互作用,研究简并喇曼相互作用过程中产生场-原子最大纠缠态的方法,实现量子逻辑门的方法,以及如何利用这种方法来实现未知原子态的量子隐形传送.     

Quantum Teleportation via Hybrid Entangled States

In this paper, we study quantum teleportation of atomic states via a hybrid entangled state (HES) involving an atom and a cavity field. And we investigate how to implement controlled phase (CP) gates between atomic internal states and coherent states of cavity field. We also discuss the methods of distinguishing coherent states |±α〉in a cavity. Finally, a brief discussion about the feasibility of this scheme in experiment is presented.     

Generation of cluster states for cavity fields

This paper proposes an alternative scheme for generating cluster-type of entangled coherent states. This scheme is based on resonant interaction of a two-mode cavity with a two-level atom driven by strong classical fields. Thus the required interaction time is greatly shortened, which is very important in view of decoherence.     

增光子二模纠缠相干态的纠缠特性及其通过腔量子电动力学的制备

分析了增光子二模纠缠相干态的纠缠特性,得到共生纠缠度的解析表示式.结果表明:增光子二模纠缠相干态的共生纠缠度与叠加态的相位有非常灵敏的关系.提出了一种制备增光子相干态和增光子二模纠缠相干态的方法,其制备过程为首先把增光子相干态转化为相干态与真空态一种特殊的叠加态(叠加系数与相干态振幅有关),再通过位于高Q腔内的原子与经典激光场的相互作用,从而实现增光子相干态的制备.通过一个飞行原子先后与两个光腔中光场相互作用可以实现增光子二模纠缠相干态的制备.     

利用两能级原子与腔场的相互作用转移纠缠

分析了大失谐情况下一个两能级原子和相干态腔场相互作用的特点;讨论了利用两能级原子和相干态腔场相互作用制备纠缠相干态的方法;提出了一个关于纠缠相干态的纠缠转移的方案。在这个纠缠转移的方案里,通讯伙伴之间使用的量子信道是由两个振幅相同位相相反的相干态构成的纠缠态。通过使用两能级原子和腔肠相干态的相互作用和两模正交态测量并在经典信息的帮助下完成了三个通讯伙伴之间的纠缠转移。随着近来腔量子电动力学技术的发展,这个方案是能够被实行的。     

增光子二模纠缠相干态的纠缠特性及其通过腔量子电动力学的制备

分析了增光子二模纠缠相干态的纠缠特性,得到共生纠缠度的解析表示式.结果表明:增光子二模纠缠相干态的共生纠缠度与叠加态的相位有非常灵敏的关系.提出了一种制备增光子相干态和增光子二模纠缠相干态的方法,其制备过程为首先把增光子相干态转化为相干态与真空态一种特殊的叠加态(叠加系数与相干态振幅有关),再通过位于高Q腔内的原子与经典激光场的相互作用,从而实现增光子相干态的制备.通过一个飞行原子先后与两个光腔中光场相互作用可以实现增光子二模纠缠相干态的制备.     

Generation of Cluster-Type Entangled Coherent States via Cavity QED

In this paper, we present a scheme for generating cluster-type entangled coherent states via cavity QED. The scheme is based on the off-resonant interaction between one atom and N cavities, so the spontaneous emission of the atom can be ignored. The initial states of the N cavities are all prepared in vacuum states. We also discuss the experimental feasibility.     

Generation of entangled coherent states for two cavity modes via resonant interaction with a V-type three-level atom

This paper proposes a scheme for the generation of entangled coherent states for two cavity modes. In the scheme a V-type three-level atom is sent through a two-mode cavity filled with a coherent field. After the atom cavity interaction and detection of the atomic state the cavity modes may evolve to a superposition of two-mode coherent states. As the scheme is based on resonant atom-cavity interaction, the required interaction time is short, which is important in view of the decoherence. Moreover, additional classical pulses are unnecessary before and after the atom-cavlty interaction.     

通过Raman相互作用隐形传送未知多原子纠缠态

基于多粒子纠缠态在证明量子非定域性和量子信息处理方面的重要应用,提出一种方案隐形传送未知原子纠缠态.方案基于Λ型三能级原子与单模腔场的简并Raman相互作用.首先让n个原子相继通过一个相干腔场来制备量子通道.然后发送者让携带未知纠缠态的另n个原子相继通过相干腔场并通过对原子与腔场的探测作联合测量.当｜α｜1时,可以用探测正交态的方法探测腔场.最后接收者根据由经典通道得到的联合测量结果重构初始态.方案的特点是用一个相干态与多个原子的纠缠态作为量子通道,简单易行.该方案有望在证明量子非定域性和量子信息过程中有重要的应用价值.     

纠缠相干态的制备

在非线性克尔介质和光场的相互作用基础之上,提出了一个纠缠相干态(包括多模和高模纠缠)的光学实现方案。发现通过适当选择场的初态,相互作用时间和广义贝尔测量,能产生多模和高维纠缠相干态。同时发现当输入模的态为相干态和叠加数态的情况下,非线性克尔相互作用可产生纠缠。     

三能级原子与奇偶纠缠相干光作用的光场压缩

采用求解薛定谔方程和数值计算方法,研究了V型三能级原子与双模奇偶纠缠相干光场相互作用过程中的光场压缩效应,讨论了压缩效应与双模奇偶纠缠相干光场的纠缠程度、系统失谐量、双模光场的平均光子数和原子基态概率幅的依赖关系。结果表明：光场压缩效应与双模奇偶纠缠相干光场的纠缠程度、失谐量、平均光子数和原子初态相关联：双模纠缠相干光场处于非纠缠状态时的光场压缩量比光场处于纠缠状态时要大;原子处在单纯的基态或激发态时光场都有明显的压缩现象出现;而原子初态中基态和激发态的概率幅较接近时无光场压缩现象;无论光场是否处于纠缠态,只有两模平均光子数接近时,光场才会出现压缩效应。     

Generation of W-Type Entangled Coherent States of Three-Cavity Fields by a Driving Classical Field

A scheme is proposed to generate the W-type entangled coherent states of three-cavity field. The scheme is based on the resonant atom-field interaction, thus the interaction time between the atom and the cavity is greatly reduced, which is important in view of decoherence. Furthermore, the scheme does not need accurate adjustment of the interaction time.     

Entangling distant atoms by interference of polarized photons

We propose a scheme to generate the entangled state of two Lambda-type three-level atoms trapped in distant cavities by using interference of polarized photons. Two possible spontaneous emission channels of each excited atom result in a coherent superposition of the states of two atoms. The subsequent detection of the different polarized photons reveals that both atoms are in different ground states, but an interference effect prevents us from distinguishing which atom is in which ground state; the atoms are thus entangled. In comparison with the original proposal of interference-induced entanglement [C. Cabrillo, J. Cirac, P. Garcia-Fernandez, and P. Zoller, Phys. Rev. A 59, 1025 (1999)]], in our scheme the weakly driven condition is not required, and the influence of atomic excitement and atomic recoil on the entanglement fidelity can be eliminated.     

Optical Generation of Single- or Two-Mode Excited Entangled Coherent States

With nonlinear Mach-Zehnder interferometer （NLMZI） and a typed beta-barium borate （BBO） crystal, we optically generate single-mode excited entangled coherent states. This scheme can be easily generalized to generate two-mode excited entangled coherent states. We simply analyse different influences of single- and two-mode photon excitations on entangled coherent states.     

利用原子-腔场喇曼相互作用制备纠缠压缩真空态

提出了利用量子态腔场与原子的喇曼相互作用制备纠缠压缩真空态的方案.在该方案中,一个初始制备在基态的原子被依次送入几个初始制备在压缩真空态的微腔中.通过控制原子的运行速度,使原子与每一个腔具有相同的相互作用时间.当原子与腔场发生相互作用,原子与腔场产生纠缠之后,进行原子的测量.当原子被测量处于基态或激发态时,按照量子力学波包塌缩原理,腔场态将塌缩到相应的纠缠压缩真空态.对纠缠压缩真空态的纠缠性质也进行了简略的讨论.     

Generation of Vibrational Entangled Coherent States of Two Trapped Ions

We propose a scheme for the generation of entangled coherent states for the center-of-mass and relative vibrational modes of two trapped ions. In the scheme the ions are simultaneously illuminated by a single standing-wave laser tuned to the carrier. The scheme allows the production of an entangled coherent states with a considerably high speed as long as a laser field of sufficiently high intensity is available.     

Generation of Vibrational Entangled Coherent States of Two Trapped Ions

We propose a scheme for the generation of entangled coherent states for the center-of-mass and relative vibrational modes of two trapped ions. In the scheme the ions are simultaneously illuminated by a single standing-wave laser tuned to the carrier. The scheme allows the production of an entangled coherent states with a considerably high speed as long as a laser field of sufficiently high intensity is available.