耦合量子点激子自旋弛豫机制研究

项目名称： 耦合量子点激子自旋弛豫机制研究

项目编号： No.11464034

项目类型： 地区科学基金项目

立项/批准年度： 2015

项目学科： 数理科学和化学

项目作者： 赵翠兰

作者单位： 内蒙古民族大学

项目金额： 50万元

中文摘要： 单量子态的检测和相关物理研究是量子通信和量子计算领域的关键科学问题。近年来，以半导体量子点中单电子（空穴）自旋、核自旋及耦合量子点中激子为基本量子比特及操作的研究成为大家关注的重点。而耦合量子点中电子（空穴）自旋弛豫和激子自旋弛豫的研究还较少。鉴于耦合量子点物理研究的重要性及相应测量技术的需求，本项目提出生长制备低密度垂直耦合InAs 量子点样品，通过外加电场调谐激子形成直接激子或间接激子，在低温和外加纵向磁场下，利用飞秒激光脉冲准共振激发量子点，测量直接激子和间接激子自旋相关的瞬态偏振荧光光谱，得到不同温度和磁场强度下耦合量子点中激子的自旋弛豫时间；结合激子占据速率方程及声子辅助费米-黄金跃迁公式，分析研究耦合量子点中激子自旋弛豫机制。这些研究内容及测量技术为今后在固态体系中拓展构筑多量子比特及有效地操作激子自旋提供前期研究基础。

中文关键词： 垂直耦合InAs量子点；激子自旋弛豫；时间分辨光谱；自旋轨道耦合；超精细相互作用

英文摘要： Study on single quantum state measurement and related the physics are very important for the fields of quantum information and quantum coupution.Recent years, as a basic qbuit,it becomes a focusing hot research field for investigating and manipulating electron (hole) spin,nuclear spin and exciton in semiconductor quantum dots(QDs) and coupled quantum dots(CQDs).At present,only few published papers were related to the study on electron (hole) spin relaxation and exciton relaxation in CQDs.Considering the importance and requirement underlying CQD physics and measurement technique, in this proposal we firstly fabricate vertically coupled InAs QD samples with a low density. The exciton can be tunned between the exciton state and indirect exciton state through applied electric field. At low temperature and vertical magnetic field (Faraday configuration), polarization and time-resolve photoluminescence spectra of both exciton and indirect exciton can be measured using Ti-sapphire laser quasi-resonant pumping the CQDs.Then we can obtain the exciotn spin lifetimes under different temperature and magnetic field.Based on the exciotn rate equation and phonon-scattering-mediated Fermi's golden rule,the underlying mechanism of exciton spin relaxation will be analyzed.These studies will help to build qubit in the solid system and effectively manipulate exciton spins for further investigation.

英文关键词： vertical coupled InAs quantum dots;exiton spin relaxation;time-resolved photoluminescence;spin-orbit interaction;hyperfine interaction