连续变量量子离物传态的实验研究

Experimental study of continuous-variable quantum teleportation

利用单个Ⅱ类相位匹配OPA产生的双模压缩态实现连续变量压缩纠缠态,完成了连续变量量子离物传态.Ⅱ类相位匹配OPA参量反放大过程可以实现正交振幅反关联、正交位相关联的压缩纠缠态,这不同于一般运转于阈值以下的OPO产生的正交振幅关联、正交位相反关联的压缩纠缠态,可以采用直接平衡测量的方法完成Bell态测量.利用双KTP补偿非线性过程的离散效应,获得了最大压缩大于2dB的双模压缩纠缠态,实现保真度0.6,考虑到探测效率实际保真度为0.57.这种方案简化了测量方法与纠缠光源产生装置,有利于进行量子通信的实验研究与应用.同时,讨论了探测过程中的一些非理想因素.

The experimental demonstration of quantum teleportation for continuous variables using the squeezed-state entanglement generated by a type II phase matching optical parametric amplifier(OPA) is reported. Type II OPA operating at deamplification can generate amplitude-anticorrelated and phase-correlated entanglements, which can be used in quantum teleportation scheme by direct Bell- state measurement. The correlation of 2dB was obtained with a pair of KTP crystals in the cavity. The inferred teleportation fidelity is 0.60, which when correlated for the efficiency of detection by the output observer, gives a fidelity of 0.57. The imperfect factors in detection are also. discussed.