Spectral theory of Liouvillians for dissipative phase transitions

Understand

A state of an open quantum system is described by a density matrix, whose dynamics is governed by a Liouvillian superoperator.

• Within a general framework, we explore fundamental properties of both first-order dissipative phase transitions and second-order dissipative phase transitions associated with a symmetry breaking.
• In the critical region, we determine the general form of the steady-state density matrix and of the Liouvillian eigenmatrix whose eigenvalue defines the Liouvillian spectral gap.
• We illustrate our exact results by studying some paradigmatic quantum optical models exhibiting critical behavior.