传送两原子直积态的腔QED方案(英文)

本文提出一个基于原子和腔场共振相互作用传送未知原子直积态的腔QED方案,原子和腔场通过J-C哈密顿量发生共振相互作用.在这个方案里,我们只需要用两个原子接受被传送的原子态以及两个单模腔作为量子通道.该方案既不需要贝尔态测量,也不需要任何操作重构纠缠初态,并且传送成功的概率为100%.这个方案也可以推广到传送n个原子的直积态.     

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.     

基于腔QED制备W纠缠态（英文）

本文基于腔QED提出了一种制备双光子四粒子体系W纠缠态的新方案.该方案通过双光子过程,利用一个三能级原子与四个腔场发生非共振相互作用制备出具有最大保真度的W纠缠态.要求四个腔场最初处于真空态,原子最初处于激发态,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.并且通过讨论表明该方案具有一定的实验可行性.     

基于腔QED的多用户间的多原子量子信道的建立

提出基于腔QED技术的多用户间的多原子W态和GHZ态量子信道的建立方案.在量子网络的空闲时段,各个用户和量子交换机共享EPR对.量子交换机通过原子和腔场的相互作用将两个EPR对制备成W态,再与另一个EPR对进行纠缠交换,经过直接测量后为用户建立三原子W态量子信道;同时讨论了四用户间的W态量子信道的建立方案.量子交换机对三个EPR对进行纠缠交换,将三个原子同时与腔场作用,经过直接测量后为用户建立三原子GHZ态量子信道;并将此方法推广到N个用户间的GHZ态量子信道的建立. 关键词： 腔QED 量子信道 量子交换机 纠缠交换     

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.     

利用腔QED技术控制传输任意两原子态

我们提出一个利用腔QED技术控制传输任意两原子态的方案.在此方案中,我们选择一个GHZ态和一个EPR对作为量子通道.在控制者的帮助下,发送者可以把量子信息传送给接收者.在传输过程中,两对原子分别与两个全同单模场相互作用,同时两对原子分别由两个全同经典场驱动.该方案对腔衰变和热场不敏感,并且传输成功的几率为1.     

基于腔QED制备四粒子supersinglets

在双光子跃迁下,本文基于腔量子电动力学(QED)系统提出了一种制备4粒子supersinglets的方案.方案要求腔场最初处于真空态,依次与四个腔场发生共振作用的三能级原子最初处于激发态.分析和讨论了该方案的可行性以及原子-腔场的耦合常数对保真度的影响.结果表明：1)该态保真度的值随原子与腔场相互作用时间的不同而不同,选择合适的原子-腔场相互作用过程以及对原子态的探测,可获得具有最大保真度的纠缠态;2)失谐量等于零时,耦合常数越大,保真度对原子与腔场相互作用的时间越敏感.     

利用三原子W类纠缠态在腔量子电动力学体系中实现单原子态的远程制备

提出了两个利用三原子W类纠缠态作为量子通道.在腔量子电动力学(QED)体系中实现单原子态的远程制备方案:一个是接收者借助于原子与单模腔场之间的大失谐相互作用实现初始态重建,另一个则是接受者利用原子与单模腔场之间的共振相互作用完成远程态制备.两方案中都涉及到了一位发送者和两位接收者,发送者可以将被传送态远程制备到两位接收者中的任何一位的手中,而另一位接受者必须为其提供必要的协助.表明利用原子与腔场之间的大失谐相互作用的方法可以很好地克服腔场的消相干,降低对腔品质因子的要求;而利用共振相互作用的方法则无需引入辅助原子,操作简便.但不论采用何种方法,实现单原子远程态制备的总成功概率是相同的.     

基于腔QED的隐形传送四比特团簇类态方案

本文提出了一个基于腔QED的隐形传送四比特团簇类态方案,在该方案中选用两个GHZ纠缠对作为量子通道,通过对原子和腔场的大失谐作用以及外加强经典场的辅助,可以制备纠缠的量子通道,完成联合的三粒子测量,成功地实现隐形传送四比特团簇类态。结果还表明,此方案不受腔场退相干和热场的影响.     

利用纠缠交换制备原子-原子最大纠缠态

基于腔量子电动力学(QED)提出一种利用两对纠缠的级联型三能级原子与单模腔场系统制备原子-原子最大纠缠态的简单方案,最初两原子之间、两腔场之间互不纠缠,使其中一个原子与一个腔场发生作用,即纠缠交换,该过程仅需对单个腔场态测量就可实现从未有直接作用的两个原子之间的纠缠,精确控制原子与腔场的相互作用时间可获得具有最大保真度的纠缠态.该方案可以延长腔的有效泄漏时间,从而能有效克服光腔的消相干的影响,这样大大降低了系统对腔的品质的要求.     

Quantum State Transfer for Two Atoms with a Single Resonant Interaction

We present a scheme for transferring an unknown atomic entangled state with a single resonant interaction. This scheme only requires a single resonant interaction of two atoms with a cavity mode and does not use the cavity mode as the memory. Thus the scheme is very simple and the interaction time is very short, which is important, in view of decoherence. Quantum state can be directly transferred from two atoms to another two at, oms with a successful probability of 100 percent.     

Production of three-dimensional entanglement for two atoms with a single resonant interaction

A scheme is proposed for generating three-dimensional maximally entangled states for two atoms. In the scheme the atoms are trapped in a two-mode cavity. The scheme only requires a single resonant interaction of the atoms with the cavity modes. Therefore, the scheme is very simple and required interaction time is very short, which is important in view of decoherence.     

Decoherence-immune generation of highly entangled states for two atoms

This paper proposes a decoherence-immune scheme for generating highly entangled states for two atoms trapped in a cavity. The scheme is based on two resonant atom-cavity interactions. Conditional upon the detection of no photon, the two atoms may exchange an excitation via the first resonant interaction, which leads to entanglement. Due to the loss of the excitation, the two atoms are in a mixed entangled state. With the help of an auxiliary ground state not coupled to the cavity mode, the state related to the excitation loss is eliminated by the detection of a photon resulting from the second resonant interaction. Thus, the fidelity of entanglement is almost not affected by the decoherence.     

Quantum nondemolition measurement of photon—number distribution for a weak cavity field with resonant atoms

We propose a quantum nondemolition measurement of the photon-number distribution for a weak cavity field with no more than two photons. The scheme is based on the resonant interaction of atoms with the cavity field, and thus the required interaction time is much shorter than that using dispersive interaction. This is important in view of decoherence. Our scheme can also be used to generate even and odd coherent states for a weak cavity field with resonant atoms.     

One-step generation of qutrit entanglement via adiabatic passage in cavity quantum electrodynamics

A scheme is proposed for generating a three-dimensional entangled state for two atoms trapped in a cavity by one step via adiabatic passage. In the scheme, the two atoms are always in ground states and the field mode of the cavity excited is negligible under a certain condition. Therefore, the scheme is very robust against decoherence. Furthermore, it needs neither the exact control of all parameters nor the accurate control of the interaction time. It is shown that qutrit entanglement can be generated with a high fidelity.     

A scheme for realizing n-qubit controlled-phase gates with atoms in cavity QED

We present a new scheme for realizing a n-qubit controlled-phase gate with atoms in cavity QED. The present scheme operates essentially by exchanging a single photon between the control atoms and the cavity mode before and after a phase shift performed on the target atom. It is interesting to note that the gate can be implemented in a very simple way and by employing resonant interaction with one cavity only.     

Transformation of bipartite non-maximally entangled states into a tripartite W state in cavity QED

We present two schemes for transforming bipartite non-maximally entangled states into a W state in cavity QED system, by using highly detuned interactions and the resonant interactions between two-level atoms and a single-mode cavity field. A tri-atom W state can be generated by adjusting the interaction times between atoms and the cavity mode. These schemes demonstrate that two bipartite non-maximally entangled states can be merged into a maximally entangled W state. So the scheme can, in some sense, be regarded as an entanglement concentration process. The experimental feasibility of the schemes is also discussed.     

Generation of Greenberger-Horne-Zeilinger states for three atoms trapped in a cavity beyond the strong-coupling regime

A scheme is proposed for generating maximally entangled states for three atoms trapped in a two-mode cavity. The scheme is based on resonant atom-cavity interaction and linear optics elements. The fidelity of the entangled state is not affected by both the decoherence and detection inefficiencies. The scheme works beyond the strong-coupling regime, which is important for high-fidelity entanglement engineering under realistic conditions.     

一个传送原子纠缠态的新方案

本文提出一个通过原子和腔场相互作用传送未知原子纠缠态的新方案,并且成功概率为100%.在这个方案里,我们主要利用两个原子用来接受被传送的原子纠缠态以及一个双模腔作为量子通道.由于腔场的两个模具有不同的频率和正交极化,因此这两个模能够被区分,并且处于腔场的不同区域.原子和腔场通过J-C哈密顿量发生共振相互作用,当原子和其中一个模相互作用时,另外一个模不受影响.该方案既不需要贝尔态测量,也不需要任何操作重构纠缠初态.这个方案也可以推广到传送N个原子的纠缠态.     

V-型三能级原子与双模腔场模型中的纠缠交换方案

文章利用V-型三能级原子与双模腔场双光子共振相互作用,提出了一种纠缠交换的方案制备最大纠缠态,此方案不需要Bell基测量,只需对单个原子进行测量,就能实现初始没有直接相互作用的原子与腔场之间产生纠缠,合适选择原子与腔场之间的相互作用时间可获得具有最大保真度以及成功几率的最大纠缠态,另外,还讨论了该方案的实验可行性.