具有经典相干性的两组EPR纠缠态光场的实验产生

Experimental generation of two EPR entangled states with classical coherence

纠缠交换,即纠缠态的量子离物传送,是实现远程量子通讯及量子信息网络的必要手段之一.要完成纠缠交换实验,首先必须具有两组相互独立的纠缠源.对于连续变量系统,两独立的纠缠源为具有经典相干但量子起伏互不关联的两组EPR纠缠态光场.利用自行研制的瓦级连续双波长输出Nd3+YAP KTP稳频激光器为抽运源,抽运两台结构完全相同的非简并光学参量放大器,获得了具有经典相干性的两组独立的EPR纠缠光束.讨论了两组具有经典相干性的EPR光束产生的实验方法,及不完善模匹配效率对关联测量的影响.

Quantum entanglement swapping, i.e. the teleportation of entanglement state, is a basic method used for developing quantum communication and quantum information network. It is necessary to produce two independent entangled states for implementing the quantum entanglement swapping. To experimentally demonstrate the entanglement swapping of continuous variables, we should firstly generate two electron paramagnetic resonance(EPR) entangled states with classical coherence and without any correlation of quantum fluctuation. Using a home-made continuous Nd3+ YAP/KTP laser to pump two nondegenarate optical parametric amplifiers with the same configuration, we obtained a pair of independent EPR entangled states with classical coherence. The experimental technology of generating two sets of EPR beams is introduced and the influence of mode match on the detection of quantum correlation is discussed.