脉冲光场作用下纠缠双光子量子相干特性研究

摘要

基于非线性光学和量子理论,分析了脉冲激光泵浦的第二类型自发参量下转换产生的纠缠双光子波函数及双光子振幅关联特性.研究了纠缠双光子对的量子相干性质,并与泵浦源为连续时双光子量子相干性质做了对比.数值计算得到了二阶相关函数及平均符合计数率的演化规律.结果表明,随着激光脉冲宽度的增加,相位匹配函数的不对称性增加,纠缠光子对的相干性(不可区分性)减小,量子干涉可见度下降.%Based on the nonlinear optics and quantum theory, the wave function and the correlated properties of entangled hi-photon with spontaneous type-Ⅱ parametric down-conversion pumped by a pulse laser are analyzed. The quantum coherent properties of entangled hi-photon are investigated and compared with that of the bi-photon pumped by a continuous wave (CW) laser.The evolution regularity of the second-order correlation function and average coincidence counting rate are obtained by numerical calculation. The results show that as increasing the pump band-width, the asymmetry of the phase-matching function is increased, and then the coherence (distinguishability)of entangled bi-photon and quantum interference visibility are diminished.