项目名称： 激子极化激元的拓扑相变及其约瑟夫森效应

项目编号： No.61504039

项目类型： 青年科学基金项目

立项/批准年度： 2016

项目学科： 无线电电子学、电信技术

项目作者： 张传意

作者单位： 河南大学

项目金额： 18万元

中文摘要： 拓扑相变已成为当前国内外物理学研究的热点，其研究对象主要集中在电子等费密子上。然而，关于有非线性相互作用的玻色子的拓扑相变则很少有报道。在本项目中，申请者以半导体量子阱中的激子极化激元为例，讨论耦合型玻色子的拓扑相变。在该玻色子凝聚体的六角晶格结构中，我们采用格点模型，对哈密顿量进行对角化，获得非简并基态。通过贝里连接定义系统的拓扑指数，研究系统的拓扑性质以及实验上的测量方式，重点探讨相互作用对拓扑指数的影响。在此基础上，通过外场的调控，改变系统的拓扑指数，让其发生拓扑相变，探索这一过程中物理性质的变化情况。最后，通过凝聚体的约瑟夫森结，讨论拓扑相变对约瑟夫森流的影响，尤其是相变点处流的变化。我们的研究不仅扩展拓扑相变的研究范围，其研究方法可以运用到其它有相互作用的玻色子上，而且可以丰富人们对玻色子拓扑相变的认识，并为设计有特殊功能的小型器件提供理论基础。

中文关键词： 激子极化激元；非线性相互作用；拓扑相变；约瑟夫森效应；外场调控

英文摘要： Topological phase transition has become a hot topic for domestic and overseas researchers in physics at present, and its research object mainly focuses on fermions like electron. But there are few reports on the topological phase transition of bosons with nonlinear interaction. In this project, the applicants will take exciton polaritons in a semiconductor quantum well for example, and discuss the topological phase transition of coupled bosons. In the hexagonal structure of exciton-polariton condensate, we will use the lattice model, diagonalize the Hamiltonian of system, and obtain the wave function of the non-degenerate ground state. By the Berry connection, we will define the topological index, investigate the topological properties of the system and method of measurement in experiment, and pay much attention to the influence of interaction on the topological index. On this basis, we will change the index by the modulation of external fields, let the topological phase transition occur, and then explore the physical properties in this process. Finally, the effect of phase transition on the Josephson current will be discussed by the condensate Josephson junction, especially at the transition point. Our study will not only extend the research scope of topological phase transition where the method can be applied to other bosons with interaction, but enrich the cognition of topological phase transition of bosons and provide the theoretical basis for designing small devices with specific functions.

英文关键词： exciton polariton;nonlinear interaction;topological phase transition;Josephson effect;modulation of applied fields