Department of Physics

Physics Colloquium

DATE:           Friday, November 20, 2015
TIME:           12:20 pm - 1:30 pm
LOCATION:   205 Campbell Hall

"Photon Berry Phases, Instantons, Schrodinger Cats with Oscillating Parities and Photon Correlation Functions in Cavity QED Systems"

Dr. Jinwu Ye
Department of Physics
Mississippi State University


The four standard quantum optics models such as Rabi, Dicke, Jaynes-Cummings (JC) and Tavis-Cummings (TC) models were proposed by the old generation of great physicists many decades ago. Despite their relative simple forms and many previous theoretical works, their solutions at a finite N, especially inside the superradiant regime, remain unknown. In this work, we resolve this outstanding problem by using three independent methods such as 1/J expansion, the strong coupling expansion and exact diagonization to study the U(1)/Z2 Dicke model at a finite N. This model includes the four standard quantum optics model as its various special limits. At a finite N, we identify 3 different regimes of the system's energy levels: the normal,U(1), and quantum tunneling (QT) regime. We compute the photon correlation functions, squeezing spectrum and number correlation functions. We find nearly perfect agreements among the 3 methods not only in the QT regime, but also in the U(1) regime not too close to the superradiant transition point. Various experimental realizations and detections are discussed. Finally, we also briefly mention the decoherence effects on the Schrodinger Cats, some variants of the U(1)/Z2 Dicke models and also the prospects of circuit lattice systems. This talk will be given in a pedagogical way, such that it will be accessible to graduate students and postdoctoral fellows.