报告题目：Hidden continuous symmetry in two-mode cavities（双模光学腔中的隐含连续对称性）
报 告 人：陈刚教授（山西大学激光光谱研究所）
报告时间：2017年3月14日（周二）14：00
报告地点：校本部G309
邀请人：张永平 教授
报告摘要：
In this take we first show that a two-mode Dicke model exhibits a hidden continuous U(1) symmetry and thus the gapless excitation spectrum. Based on this property, we then construct a new type of cavity array, which is governed by a two-mode Dicke-lattice model. Attributed to its special atom-photon coupling scheme, this lattice model also supports a global conserved excitation and a continuous U(1) symmetry. This distinct change of symmetry via adding an extra photon mode strongly impacts the nature of photon localization/delocalization behavior. Specifically, the atom-photon interaction features stable Mott-lobe structures of photons and a second-order superfluid-Mott-insulator quantum phase transition. More interestingly, the Mott-lobe structures predicted here depend crucially on the atom number of each site. Finally, we propose a scheme to implement the introduced cavity array in circuit quantum electrodynamics. Our results pave the way to explore the physics for a model with continuous symmetry in quantum optics without using the rotating-wave approximation.
