Non equilibrium dynamics of an optomechanical Dicke model
  Motivated by the experimental realization of Dicke model in optical cavities, we model an optomechanical system consisting of a two level BEC with transverse pumping. We investigate the transition from normal and inverted state to the superradiant phase through a detailed study of the phase portrait of the system. The rich phase portrait generated by analytic arguments displays two types of superradiant phases, regions of coexistence and some portion determining the persistent oscillations. We study the time evolution of the system from any phase and discuss the role of mirror frequency in achieving the attractors and stable values. Further, we add an external mechanical pump to the mirror which is capable of changing the mirror frequency and study the impact of the pump on the phase portraits and the dynamics of the system. We find the external mirror frequency changing the phase portraits and even shifting the critical transition point, thereby predicting a system with controllable phase transition. 
Kamanasish Debnath and Aranya B. Bhattacherjee
quant-ph