量子点操控的光子探测和圆偏振光子发射  

Single photon detection and circular polarized emission manipulated with individual quantum dot

作　　者：李天信[1] 翁钱春[1,2] 鹿建[3] 夏辉 安正华[3,4] 陈张海[3] 陈平平[1] 陆卫[1] Li Tian-Xin;Weng Qian-Chun;Lu Jian;Xia Hui;An Zheng-Hua;Chen Zhang-Hai;Chen Ping-Ping;Lu Wei(National Laboratory for Infrared Physics,Shanghai Institute of Technical Physics,Chinese Academy of Sciences,Shanghai 200083,China;Key Laboratory of Polar Materials and Devices,Ministry of Education,East China Normal University,Shanghai 200241,China;State Key Laboratory of Surface Physics and Institute of Advanced Materials,Fudan University,Shanghai 200433,China;Key Laboratory of Micro and Nano Photonic Structures（Ministry of Education）Fudan University,Shanghai 200433,China)

机构地区：[1]中国科学院上海技术物理研究所,红外物理国家重点实验室,上海200083 [2]华东师范大学,极化材料与器件教育部重点实验室,上海200241 [3]复旦大学,表面物理国家重点实验室,先进材料研究所,上海200433 [4]复旦大学,微纳光子结构教育部重点实验室,上海200433

出　　处：《物理学报》2018年第22期99-110,共12页Acta Physica Sinica

基　　金：国家自然科学基金(批准号:91321311;11574336);上海市科委基础研究项目(批准号:18JC1420400)资助的课题~~

摘　　要：半导体量子点是研究光子与电子态相互作用的优选固态体系,并在光子探测和发射两个方向上展现出独特的技术机遇.其中基于量子点的共振隧穿结构被认为在单光子探测方面综合性能最佳,但受到光子数识别、工作温度两个关键性能的制约.利用腔模激子态外场耦合效应,有望获得圆偏振态可控的高频单光子发射.本文介绍作者提出的量子点耦合共振隧穿(QD-cRTD)的光子探测机理,利用量子点量子阱复合电子态的隧穿放大,将QD-cRTD光子探测的工作温度由液氦提高至液氮条件,光电响应的增益达到10~7以上,并具备双光子识别能力;同时,由量子点能级的直接吸收,原型器件获得了近红外的光子响应.在量子点光子发射机理的研究方面,作者实现了量子点激子跃迁和微腔腔模共振耦合的磁场调控,在Purcell效应的作用下增强激子自旋态的自发辐射速率,从而增强量子点中左旋或右旋圆偏振光的发射强度,圆偏度达到90%以上,形成一种光子自旋可控发射的新途径.Studies on quantum dots（QDs） provide great opportunities in single photon detection as well as single circular polarized photon emission, which are the key technology for future quantum information processing. For single photon detection, the quantum-dot-resonant-tunneling-diode（QD-RTD） is evaluated as one of the most promising scheme but still suffering from the ultralow working temperature（～5 K） and lack the capability to discriminate photon numbers.Here we demonstrate a photon-number-resolving detector based on quantum dot coupled resonant tunneling diodes（QD-cRTD）. Individual QDs coupled closely with adjacent quantum well（QW） of resonant tunneling diode operate as photon-gated switches which turn on（off） the RTD tunneling current when they trap photon-generated holes（recombine with injected electrons）. With proper decision regions defined, 1-photon and 2-photon states are resolved in 4.2 K with excellent propabilities of accuracy of 90% and 98% respectively. Further, by identifying step-like photon responses,the photon-number-resolving capability is sustained to 77 K, making the detector a promising candidate for advanced quantum information applications where photon-number-states should be accurately distinguished. On the other hand,we firstly performed the magneto-optical studies on single InGaAs/GaAs self-assembled QDs. We observed the exciton Zeeman splitting and diamagnetic shift of a single QD under magnetic field, and the exciton g factor and diamagnetic coefficient was extracted by fitting the magnetic field dependent PL energies. By comparing with theories, we discussed on the effect of QD size, shape and composition on these two parameters. Based on these work, we investigated the single QD exciton-cavity mode coupling effect under external magnetic field. By first time we observed the interaction of Zeeman splitted exciton spin states with the cavity mode and realized the selective enhancement of the SE rate of the exciton state with specific spin configuration by mean

关 键 词：单光子探测 单光子发射 量子点 光学微腔 

分 类 号：O471.1[理学—半导体物理]