冷原子系综中量子关联光子对的产生

The Generation of Quantum Correlated Photon Pairs in Cold Atomic Ensemble

本文在87 Rb冷原子系综中通过自发拉曼散射过程进行了量子关联光子对产生的实验研究,测量了关联光子对的产生率和二阶关联函数g(2)随写光激发率、读光功率以及写光失谐等实验参数的关系曲线。结果表明:随着写光激发率的增加,光子对产生率线性增加,g(2)则不断减小;在小的读光功率处,光子对产生率和g(2)随着读光功率增加而增大,当读光功率超过30 mW后,产生率和g(2)随着读光功率增加反而有所下降;写光频率失谐为-5 MHz时光子对产生率和g(2)均达到最低,增大或减小写光失谐产生率和g(2)均逐渐增加。通过选取合适的实验参数,光子对产生率达到18对/秒,同时g(2)为106。本文的研究结果为产生高质量的纠缠源提供了实验基础。

We used the Spontaneous Raman scattering of the 87 Rb cold atomic ensemble to generate the quantum correlated photon pairs.In our experiment,we measured the influence of the excitation probability of writing light field,the writing light field detuning and the power of the reading light field to the secondorder correlation function and coincidence counts.The results showed that as the the writing light field excitation probability increases,the g（2）of the quantum correlated photon pairs decrease gradually.The generation rates and the g（2）of the quantum correlated photon pairs increase with the low power of the reading light field. When the reading light field is added to 30 mW,the g（2）and coincidence counts decreases instead of increaseng.As the detuning of writing light field is-5 MHz,the generation rates and the g（2）of the correlated photon pairs are the lowest.Either to increase or to decrease the detuning,the generation rates and the g（2）increase.By choosing the proper parameters,the generation rates reach 18 pairs per second with the g（2）is 106.The conclusion of this paper provides an experimental basis for generating high quality entanglement source.