报告人：Jinwu Ye,美国密西西比州立大学

报告时间：7月1日下午3:00

报告地点：清华大学高等研究院 科学馆322报告厅

报告题目：Superradiance, Photon phase diffusion, Berry phase and number squeezed state of cold atoms or superconducting qubits inside a cavity

报告摘要：Recently, strong coupling regimes of BEC atoms inside an optical cavity and superconducting qubits, quantum dots, electron spins inside a micro-wave circuit cavity were achieved experimentally. The strong coupling regimes in all these systems can be described by the Dicke model. Here we study the cavity transmission and Fluorescence spectra by solving the Dicke model by $ 1/ N $ expansion. In the normal state, we find a $ \sqrt{N} $ behavior of the collective Rabi splitting consistent with the experimental data. Inside the superradiant phase, we identify a high frequency mode and also an emergent quantum phase diffusion mode with a corresponding Berry phase at a finite $ N $ and determine their corresponding spectral weights. We also work out many remarkable experimental consequences of this quantum phase mode such as its low frequency, high spectral weight, consecutive photons plateaus, photon number squeezing properties and photon statistics. We argue that recent experimental advances in both cold atoms and semiconductor systems should motivate a new emerging interdisciplinary field of quantum optics and quantum phases which can be dubbed as " Strongly correlated quantum optics".