自发参量下转换产生的偏振纠缠光子对长寿命量子存储

项目名称： 自发参量下转换产生的偏振纠缠光子对长寿命量子存储

项目编号： No.11475109

项目类型： 面上项目

立项/批准年度： 2015

项目学科： 数理科学和化学

项目作者： 王海

作者单位： 山西大学

项目金额： 80万元

中文摘要： EPR纠缠光子的产生及其长寿命存储是进行长距离量子通讯和可扩展光量子计算的一个重要工具。通过光学腔内II-类参量下转换过程可产生出窄带偏振纠缠光子对。通过电磁感应透明（EIT）动力学过程能实现偏振纠缠光子在原子系综中的有效存储，进而实现光与原子或原子与原子间的量子纠缠。然而，由于磁场噪声导致的退相干效应，原子系综中的量子记忆寿命仅达到微秒量级。这种短的存储寿命成为长距离量子通讯和大尺度Cluster纠缠态产生的障碍。 本项目拟实现长寿命的量子纠缠记忆。 拟采用EIT动力学过程存储参量下转换产生的窄带偏振纠缠光子对,实现原子系综间的量子纠缠存储。通过施加一中等强度的磁场消除原子的Zeeman能级简并性，使偏振量子比特存储在两个磁不敏感自旋波上，获得毫秒量级的量子纠缠存储. 在此基础上，探索无退相干子空间量子纠缠存储,实现更长寿命的原子记忆量子纠缠。

中文关键词： 量子光学；量子物理；量子纠缠；量子信息；冷原子物理

英文摘要： The generations of EPR entangled photons and their long-lived storages are an important tool for implementing long-distance quantum communications and large-scale quantum calculations. By using type-II spontaneous parametric down conversions in an optical cavity, the narrow-band polarization-entangled photon pairs can be generated. Using dynamic electromagnetic induced transparency (EIT) process, the polarization-entangled photons can be effectively stored in atomic ensembles and then the quantum entanglement between light and atoms or atoms and atoms has been realized. However, limited by decoherence induced by magnetic field noise, the storage lifetimes are several microseconds. Such short lifetime is an obstacle for achiving long-distance quantum communications and large-scale cluster entanglement states. This projection focus to achieve long-lived entanglements between two atomic memories. We will use dynamic EIT to store the narrow-band polarization-entangled photons generated from parametric down conversions into atomic ensembles and then realize the quantum entanglement memories. We will apply a moderate magnetic field to remove degeneracy of atomic Zeeman sublevels, make two states of a polarization qubit store into two magnetic-field-insensitive spin waves, respectively, and thus obtain millisecond entanglement memories. Based on this, we will next explore the entanglement storages in decoherence-free subspaces and achieve atomic memory entanglwmwnt with a more longer lifetime.

英文关键词： quantum optics;quantum physics;quantum entanglement;quantum information;cold atomic physics