通信波长频率一致纠缠光源的频谱测量  

Measurement of the spectral properties of the coincident-frequency entangled biphoton state at optical communication wavelength

作　　者：王盟盟[1,2] 权润爱[1] 邰朝阳 侯飞雁[1] 刘涛[1] 张首刚[1] 董瑞芳[1] 

机构地区：[1]中国科学院国家授时中心,中国科学院时间频率基准重点实验室,西安710600 [2]中国科学院大学,北京100049

出　　处：《物理学报》2014年第19期126-131,共6页Acta Physica Sinica

基　　金：国家自然科学基金(批准号:Y133ZK1101;11174282;91336108);中科院"西部之光"计划重点项目(批准号:中科院人教字(2011)180号);科技创新"交叉与合作团队"项目(批准号:中科院人教字(2012)119号);中组部"青年拔尖人才支持计划"项目(批准号:组厅字[2013]33号)资助的课题~~

摘　　要：本文利用光栅单色仪实现了对超短脉冲抽运周期极化磷酸氧钛钾晶体产生的通信波长频率一致纠缠光子源的频谱特性分析.测量到双光子的联合频谱呈正关联分布,为频率一致纠缠光源.信号光、闲置光中心波长分别为1574.4 nm和1574.9 nm,频谱宽度分别为35.3 nm和37.6 nm,双光子符合包络宽度约为3 nm.根据单光子频谱宽度与双光子符合包络宽度的比值可以得到双光子的频率纠缠参量R约为12,表征了信号光子与闲置光子之间具有较高的频率纠缠度.The frequency entangled biphoton source generated via spontaneous parametric down-conversion（SPDC） process has found important applications in the fields of quantum clock synchronization, quantum communication, quantum information processing, etc. As quantum technologies evolve, quantitative characterization of the frequency entanglement becomes necessary and has been implemented by measuring the spectral properties of the biphoton state. However, due to the high dark rate and low quantum efficiency of the InGaAs single-photon detectors, direct measurement of the spectral properties of the biphoton state at optical communication wavelength is hard to implement. In this paper,we report the measurement of the spectral properties of a biphoton state at optical communication wavelength which is generated from periodically poled potassium titanyl phosphate（PPKTP） pumped by an ultra-short pulsed optical source at 787 nm. Based on the coincidence measurement setup together with two infrared spectrometers, the spectra of the signal and idler photons are obtained with their center wavelengths being 1574.4 nm and 1574.9 nm, while their3-dB bandwidths being 35.3 nm and 37.6 nm respectively. The joint spectrum of the photon pair is observed as well and shows a coincident-frequency entanglement and a joint spectrum bandwidth of 3 nm. According to the ratio of the singlephoton spectral bandwidth to the joint spectral bandwidth of the photon pairs, the degree of frequency entanglement is quantified to be 12, denoting a relatively high quality of the entanglement.

关 键 词：量子纠缠 联合频谱 频率正关联 

分 类 号：TM935.21[电气工程—电力电子与电力传动]