Time-delayed feedback control of the Dicke-Hepp-Lieb superradiant   quantum phase transition
  We apply the time-delayed Pyragas control scheme to the dissipative Dicke model via a modulation of the atom-field-coupling. The feedback creates an infinite sequence of non-equilibrium phases with fixed points and limit cycles in the primary superradiant regime. We analyse this Hopf bifurcation scenario as a function of delay time and feedback strength, and determine analytical conditions for the phase boundaries. 
Wassilij Kopylov, Clive Emary, Eckehard Sch\"oll and Tobias Brandes
quant-ph cond-mat.quant-gas cond-mat.stat-mech