光学腔增强Duan-Lukin-Cirac-Zoller量子记忆读出效率的研究  

Experimental study of retrieval efficiency of Duan-Lukin-Cirac-Zoller quantum memory by optical cavity-enhanced

作　　者：马腾飞 王敏杰 王圣智 焦浩乐 谢燕 李淑静[1,2] 徐忠孝 王海[1,2] Ma Teng-Fei;Wang Min-Jie;Wang Sheng-Zhi;Jiao Hao-Le;Xie Yan;Li Shu-Jing;Xu Zhong-Xiao;Wang Hai(State Key Laboratory of Quantum Optics and Quantum Optics Devices,Institute of Opto-Electronics,Shanxi University,Taiyuan 030006,China;Collaborative Innovation Center of Extreme Optics,Shanxi University,Taiyuan 030006,China)

机构地区：[1]山西大学光电研究所量子光学与光量子器件国家重点实验室,太原030006 [2]山西大学极端光学协同创新中心,太原030006

出　　处：《物理学报》2022年第2期12-16,共5页Acta Physica Sinica

基　　金：国家重点基础研究发展计划(批准号:2016YFA0301402);国家自然科学基金(批准号11475109,11974228,11604191);山西省“1331工程”重点学科建设计划(批准号:1331KSC)资助的课题。

摘　　要：量子中继是长距离纠缠分发的关键组成部分,而基于原子系综存储的读出效率是量子中继能否实用化的一个重要指标.本文利用冷原子系综中的自发拉曼散射过程产生Duan-Lukin-Cirac-Zoller量子记忆,在原子系综周围搭建环形腔,增强光与原子相互作用,从而提高读出效率,然而,腔内原子的能级分裂使量子记忆的读出效率降低.本文研究了读出效率随读光相对于原子共振线失谐量的变化关系.结果显示:当读光的失谐量为80 MHz时,本质读出效率为45%,这时腔对读出效率的增强倍数为1.68倍.Long-distance entanglement distribution is an important task for quantum communication,but difficult to achieve due to the loss of photons in optical fiber transmission.Quantum repeater is a scheme to solve this problem.In this scheme,the long distance of entanglement distribution is divided into several small parts,the entanglement is established first at both ends of each part,then,the entanglement distance is extended through the entanglement exchange of adjacent interval parts,in order to achieve the long distance entanglement distribution.Of them,the Duan-Lukin-Cirac-Zoller(DLCZ) protocol based on the cold atom ensemble and the linear optics which can generate and store entanglement,is regarded as one of the most potential schemes.In the process of DLCZ,retrieval efficiency is an important index of the quantum repeater,because it will influence each entanglement exchange operation between adjacent quantum repeater nodes.Generally,the retrieval efficiency is improved by optimizing the reading pulse,increasing the optical depth(OD) of the atomic ensemble and the cavity enhancement.The ring cavity constrains the light field to increase the intensity of the interaction between light and atoms,and effectively improve the retrieval efficiency of the quantum memory.In this work,atomic ensembles are placed in a ring cavity.The cavity length is 3.3 m and the fineness is 13.5.The optical loss of all ring cavity is 21%,mainly including 15% loss of other optical elements and 6% loss of the cell.In order to increase the retrieval efficiency,we need to ensure the mode resonance of read-out photon,write-out photon and locking.The cavity needs two input beams of light:one comes from the path of read-out photon and the other from the path of write-out photon in the reverse direction.The two beams are locked at the same frequency as the write-out photon and the read-out photon respectively.The cavity length is adjusted by moving the cavity mirrors’ positions through translating the frame,to make two light modes resonate.The

关 键 词：量子记忆 读出效率 光学环形腔 

分 类 号：O413[理学—理论物理] TN918[理学—物理]