Spontaneous T-symmetry breaking and exceptional points in cavity quantum electrodynamics systems

作     者：Yu-Kun Lu Pai Peng Qi-Tao Cao Da Xu Jan wiersig Qihuang Gong Yun-Feng Xiao 

作者机构：State Key Laboratory for Mesoscopic Physics and Collaborative Innovation Center of Quantum Matter School of Physics Peking University Beijing 100871 China Collaborative Innovation Center of Extreme Optics Shanxi University Taiyuan 030006 China Department of Electrical Engineering and Computer Science Massachusetts Institute of Technology Cambridge MA 02139 USA Institut für Physik Otto-von-Guericke-Universitat Magdeburg Postfach 4120 D-39016 Magdeburg Germany 

出 版 物：《Science Bulletin》 (科学通报（英文版）)

年 卷 期：2018年第63卷第17期

页      面：1096-1100页

核心收录：

学科分类：07[理学] 070201[理学-理论物理] 0702[理学-物理学] 

基　　金：supported by the National Key R&D Program of China(2016YFA0301302) the National Natural Science Foundation of China(61435001,11654003,11474011) High-performance Computing Platform of Peking University 

主　　题：Exceptional point Spontaneous symmetry breaking Topological singularity Cavity QED 

摘      要：Spontaneous symmetry breaking has revolutionized the understanding in numerous fields of modern physics. Here, we theoretically demonstrate the spontaneous time-reversal symmetry breaking in a cavity quantum electrodynamics system in which an atomic ensemble interacts coherently with a single resonant cavity mode. The interacting system can be effectively described by two coupled oscillators with positive and negative mass, when the two-level atoms are prepared in their excited states. The occurrence of symmetry breaking is controlled by the atomic detuning and the coupling to the cavity mode,which naturally divides the parameter space into the symmetry broken and symmetry unbroken *** two phases are separated by a spectral singularity, a so-called exceptional point, where the eigenstates of the Hamiltonian coalesce. When encircling the singularity in the parameter space, the quasiadiabatic dynamics shows chiral mode switching which enables topological manipulation of quantum states.