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.

The scheme for generating maximally entangled atom-atom states via entanglement swapping

A relatively simple scheme for the generation of maximally entangled atom-atom state is proposed, which is based on two entangled -type three-level atom-cavity systems using techniques of cavity quantum electrodynamics (QED). Initially, there is no entanglement between the two atoms, nor between the two cavity fields, and then one atom interacts with a cavity field. The scheme only requires measuring a single cavity state and precisely control the evolution time, so as to occur the entanglement of two atoms without previous interaction. More specially, The scheme can considerably prolong the effective leakage time of the cavity and overcome the decoherence effect of the cavity, thus the requirements of system on the quality of the cavity are greatly loosened. Numerical simulation results show that maximally entangled states with high fidelity can be obtained by precisely controlling the evolution time.