纠缠双原子与压缩相干态光场相互作用系统的量子纠缠

Quantum entanglement in a system of squeezed coherent state light field interacting with two entangled atoms

利用全量子理论,研究了双原子与压缩相干态光场相互作用系统的量子纠缠特性,分别讨论了相干态振幅参量、光场压缩参量和耦合系数比值对系统场熵和原子相对熵演化的影响.结果表明:当相干态振幅参量为零或很小时,两原子间纠缠度随时间演化规律和场-原子纠缠度随时间演化规律几乎相反,场-原子间的纠缠削弱了两原子间的纠缠。随着相干态振幅参量增大或光场压缩参量减小,在一定时域内,两原子处于稳定的纠缠态,并且这个时域逐渐变长,同时原子-原子平均纠缠度值增大,而场-原子平均纠缠度值减小.耦合系数比值(原子之间偶极-偶极相互作用)的增大会减弱原子与场之间的作用,使两原子始终处于最大纠缠态.

The quantum entanglement of two entangled atoms interacting with the squeezed coherent state is studied by means of full quantum theory. The influences of coherent amplitude factor, squeezing factor, ratio of two coupling coefficients on the entanglement property are discussed. The results show that two atoms entanglement evolution property is opposed to atom-field entanglement evolution property when the coherent amplitude factor was zero or small. The interaction of the atoms and field weakens the entanglement degree of atom-atom. With increasing coherent amplitude factor or decreasing squeezing factor of light, the time of two atoms staying in the steady entangled state becomes longer. The increase of the coherent amplitude factor or the decrease of squeezing factor of light lead to the increase of atom-atom entanglement degree while the decrease of atoms-field entanglement degree. Moreover, the two-atom quantum state stays in the maximum entangled state when the atomic dipole-dipole coupling coefficient is large enough.