用W态实现量子隐形传态的腔QED方案

本文提出一个用类W态作为纠缠通道,采用不同于文献[19]的测量基来实现量子隐形传态的腔QED方案.在这个方案里,只需要利用原子和腔场通过J-C哈密顿量发生共振相互作用,一步就可制备纠缠通道.另外,通过原子与腔场的失谐作用,利用Bell态测量,可实现概率为100%的量子隐形传态.在目前的腔QED技术条件下,该方案是可以实现的.     

基于法拉第旋转构造光子Bell态分析器和GHZ态分析器

基于偏振光被囚禁原子光腔反射后所获得的法拉第旋转构造了光子Bell态分析器和GHZ态分析器,并能实现非破坏地识别所有的光子Bell态和GHZ态.该方案不需要腔场的强耦合条件,在低品质光腔中也能实现,从而大大降低了实验难度.     

利用A型原子与光场的纠缠态传送腔场的奇偶相干态的叠加态

根据简并A型三能级原子与单模光场的非共振相互作用系统的改进型有效哈密顿量，利用矩阵方法推导出任意初始情况下原子—光场系统的波函数，通过改变相互作用时间，制备出原子—腔场系统的纠缠态，提出利用原子—腔场系统的纠缠态进行概率传送腔场的奇、偶相干态的叠加态的有效方案，对于振幅很大的单模光场，通过实行Bell态测量，能成功地概率传送腔场的奇偶相干态的叠加态，其成功的总概率为0.25。     

利用选择共振作用制备纠缠态

文章提出一个在高品质腔中利用选择性相互作用制备Bell态和W态的方案。该方案通过参数的选择来严格控制囚禁原子和腔场之间的相互作用,在所需要的子空间里实现共振跃迁,而让原子的其它跃迁处于大失谐,从而可以绝热去除。因此,本方案可以有效抑制原子的自发辐射,而且不需要对腔中原子独立寻址,使其在实验上更容易实现。     

利用Λ型原子与光场的纠缠态传送腔场的奇偶相干态的叠加态

根据简并Λ型三能级原子与单模光场的非共振相互作用系统的改进型有效哈密顿量，利用矩阵方法推导出任意初始情况下原子-光场系统的波函数，通过改变相互作用时间，制备出原子-腔场系统的纠缠态.提出利用原子-腔场系统的纠缠态进行概率传送腔场的奇、偶相干态的叠加态的有效方案.对于振幅很大的单模光场，通过实行Bell态测量，能成功地概率传送腔场的奇偶相干态的叠加态，其成功的总概率为0.25.     

利用非Bell基测量实现两粒子纠缠态的隐形传输

研究无Bell基测量的未知两粒子纠缠态的隐形传态方案。Alice需传送未知两原子纠缠态给Bob,以她和Bob的原子组成的最大纠缠GHZ态作为量子信道,通过两原子同时在一个强经典驱动场驱动下和一个单模腔场发生相互作用,产生态的演化,从而实现隐形传态。本方案可忽略腔场热作用和腔延迟作用的影响,传送成功的总几率为1。     

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.     

利用cluster态隐形传送任意三原子W态

提出一个隐形传送任意三原子纠缠W态的方案,在此方案中,选用由四个全同的二能级原子组成的cluster态作为量子信道.研究表明,接收者基于发送者的经典信息,借助于一个附加原子,实行联合幺正变换以及单原子幺正变换,可实现三原子W态的隐形传送.该方案不受外界热场和腔场耗散的影响,不需要贝尔态测量,成功实现传送的几率为1.     

外场驱动下腔QED中实现任意两原子态的隐形传送方案

提出了一种外场驱动下在腔QED中实现任意两原子态隐形传送的方案.在隐形传送的过程中.以两原子最大纠缠态作为量子通道,不用考虑腔场耗散和外界热场环境的影响.在传送过程中包含着对原子的Bell基测量,但不需要直接进行Bell基测量,而且最终能成功实现传送的几率为1.0.同时这种方案也可以用来传送未知的三原子GHZ态,传送的几率也为1.0.     

好腔中的Bell态原子与纠缠相干态光场相互作用系统的保真度

考虑原子间偶极相互作用,求出好腔中的Bell态原子与纠缠相干态光场相互作用系统的保真度。结果表明,对于理想腔,若原子初始时刻处于相干保持态,系统保真度始终等于1;若原子初始时刻处于其余Bell态之一,腔场初态的平均光子数很小,系统保真度在0～1之间作周期性振荡,随着腔场初态的平均光子数的增加,系统保真度的振荡频率增大,振幅减小。对于好腔,若原子初始时刻处于相干保持态,系统保真度呈指数单调衰减;若原子初始时刻处于其余Bell态之一,系统保真度呈指数振荡衰减,且随着腔场初态的平均光子数的增加,系统保真度的振荡频率增大,振幅减小。     

Scheme for Concentration of Unknown Greeberger-Horne-Zeilinger Entangled States via Cavity Decay

We present a scheme for entanglement concentration of an unknown atomic non-maximally entangled GHZ state via cavity decay. In the scheme, the atom trapped in a cavity is manipulated by laser field, so the maximally entangled GHZ state can be obtained by performing certain operation, which can be realized by illuminating the atom in a cavity. Our method is robust against spontaneous atomic decay.     

Deterministic generation of entangled coherent states for two atomic samples

This paper proposes an efficient scheme for deterministic generation of entangled coherent states for two atomic samples. In the scheme two collections of atoms are trapped in an optical cavity and driven by a classical field. Under certain conditions the two atomic samples evolve from an coherent state to an entangled coherent state. During the interaction the cavity mode is always in the vacuum state and the atoms have no probability of being populated in the excited state. Thus, the scheme is insensitive to both the cavity decay and atomic spontaneous emission.     

A scheme for transferring an unknown atomic entangledstate via cavity quantum electrodynamics

In this paper, we propose a scheme for transferring an unknown atomic entangled state via cavity quantum electrodynamics (QED). This scheme, which has a successful probability of 100 percent, does not require Bell-state measurement and performing any operations to reconstruct an initial state. Meanwhile, the scheme only involves atom--field interaction with a large detuning and does not require the transfer of quantum information between the atoms and cavity. Thus the scheme is insensitive to the cavity field states and cavity decay. This scheme can also be extended to transfer ring an entangled state of $n$-atom.     

Schemes for Generating Cluster States via Cavity Systems

We propose a scheme for generating an N-atom cluster state via cavity quantum electrodynamics （ CQED）. In our scheme, there is no transfer of quantum information between the atoms and the cavity, i.e., the cavity is always in the vacuum state, so the cavity decay can be suppressed. Also, the generated cluster state is the entanglement of the ground states, so the atomic spontaneous emission can be avoided. Therefore, the cluster state generated in our scheme has a longer lifetime. Furthermore, the requirement on the quality factor of the cavity greatly loosened for the cavity is only virtually excited.     

Controlled Dense Coding Through a Genuine Five-Atom Entangled State in Cavity QED

We present an experimentally feasible scheme for implementing controlled dense coding through a genuine five-atom entangled state in cavity QED. The scheme is insensitive to both the cavity decay and the thermal field. In the scheme that four-atom entangled states can be exactly distinguished with detecting the atomic state, and the controlled dense coding can be realized in a simple way.     

Scheme for Direct Measurement of the Wigner Function via Resonant Interaction

We propose a scheme for direct measurement of the Wigner function for a cavity mode. In the scheme the cavity field resonantly interacts with an atomic ensemble. Under certain conditions, the state of the cavity mode is transferred to the atomic system. After a displacement the measurement of the parity of the atomic excitation number directly yields the Wigner function of the initial state of the cavity mode.     

Teleportation of atomic states with a weak coherent cavity field

A scheme is proposed for the teleportation of an unknown atomic state. The scheme is based on the resonant interaction of atoms with a coherent cavity field. The mean photon-number of the cavity field is much smaller than one and thus the cavity decay can be effectively suppressed. Another advantage of the scheme is that only one cavity is required.     

利用腔QED实现量子态转移

利用两个二能级原子和用光纤联接的两个单模光腔构成的系统,给出了实现量子态转移的方案。该方案中两个二能级原子分别处于用光纤联接的单模腔中,并同时与光场发生共振相互作用。通过控制原子与光场的相互作用时间,实现量子态的转移。     

利用腔QED实现量子态转移

利用两个二能级原子和用光纤联接的两个单模光腔构成的系统,给出了实现量子态转移的方案。该方案中两个二能级原子分别处于用光纤联接的单模腔中,并同时与光场发生共振相互作用。通过控制原子与光场的相互作用时间,实现量子态的转移。     

Probabilistic teleportation of unknown atomic states using non-maximally entangled states without Bell-state measurement

We propose a physical scheme for teleporting an unknown atomic state in cavity QED. Our scheme does not involve the Bell-state measurement. The most distinctive advantage of our scheme is that teleportation and distillation procedure can be realized simultaneously. In addition, the current scheme is insensitive to the cavity decay.