Critical behavior of driven dissipative transitions : Universality beyond the Markovian regime
Open quantum systems exhibit a range of novel behavior due to the interplay between coherent dynamics and dissipation. Although these systems are intrinsically out of equilibrium, they can exhibit 'driven, dissipative transitions' that result in the emergence of dynamical phases in novel universality classes and critical behavior that lies beyond the paradigms of equilibrium phase transitions. I will discuss our experimental realization of such driven, dissipative phase transitions and our studies of the critical behavior of these systems. We find that the critical dynamics of these systems can be profoundly altered by subjecting the system to different forms of environmental correlations, leading not only to modified critical exponents but to the emergence of dynamical phases with novel broken symmetries. In particular, I will discuss one such dynamical phase that spontaneously breaks a continuous time translation symmetry. I will describe our experimental studies of the phase diagram of this non-Markovian system and the critical properties of this 'time-crystalline phase'. Extending these studies to the quantum regime, our demonstrations of reservoir engineering promise to access new forms of correlated quantum behavior that do not occur in equilibrium or Markovian systems.