Dissipative phase transitions in optomechanical systems

We show that optomechanical quantum systems can undergo dissipative phase transitions within the limit of a small nonlinear interaction and strong external drive. In such a defined thermodynamical limit, the nonlinear interaction stabilizes optomechanical dynamics in strong- and ultrastrong-coupling regimes. As a consequence, optomechanical systems possess a rich phase diagram consisting of periodic orbits and discontinuous and continuous dissipative phase transitions with and without bifurcation. We also find a critical point where continuous and discontinuous dissipative phase transition lines meet. Our analysis demonstrates that optomechanical systems are valuable for understanding the rich physics of dissipative phase transitions and ultrastrong-coupling regimes.