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A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.

A scheme was proposed to generate the W-type entangled coherent states of three-cavity fields, after comparing the differences between the discrete-variable quantum information and the continuous-variable quantum information and taking into account that coherent states were presently of practical use and readily available. The scheme was based on the degenerate Raman interaction of a A-type three-level atom with a single-mode field. Three identical cavities were in coherent states and three identical atoms shared a W-type entangled state initially. Let the three atoms interact with the three cavity fields respectively, selected a proper interaction time and detected the three atoms after exiting from their respective cavity. Then the three-cavity fields were projected onto a W-type entangled coherent states. During the atom-field interaction the atoms have no probability of being populated in the upper level, then the atomic spontaneous emissions could be neglected. Therefore, the coherence of the system might be better maintained. Based on current cavity quantum electrodynamics technique, the scheme could be realized experimentally. The W-type entangled coherent states generated was expected to be useful in the continuous-variable quantum information processing. The scheme was generalized to prepare the W-type entangled coherent states of n-cavity fields (n＞3).