Abstract: 

　　Bilayer materials may support condensates of interlayer excitons formed by electrons in one layer and holes in the other. The condensates are often induced by a voltage bias applied by electrical contacts that impose an interlayer chemical potential difference, driving the system out of equilibrium and causing the condensate phase to wind in time. We show that if charge can tunnel between the layers, this dynamical condensate has physical consequences such as an ac Josephson effect in the case of a dark condensate, and coherent photon emission in the case of a bright condensate, rendering the system in a non-equilibrium steady state (NESS). From the notion of the “Ponderomotive potential”, we determine the NESS phase diagram of the system. If the system is placed in an optical cavity, coupling with cavity photon modes favors different dynamical states depending on the bias, realizing superradiant phases. We demonstrate these phenomena in biased transition metal dichalcogenide bilayers.

报告人简介：

　　孙志远，2012年本科毕业于中国科学技术大学，2018年博士毕业于UC San Diego，2018年-2022年先后任Columbia University博士后及Harvard University HQI Fellow，2022年至今任清华大学物理系助理教授。主要从事凝聚态理论中的非平衡问题研究，集中在固体材料的光学、集体激发及光致非平衡过程。