Dynamical Phase Transitions and Instabilities in Open Atomic Many-Body Systems

TL;DR

This paper investigates a driven-dissipative quantum many-body system, revealing a nonequilibrium phase transition characterized by a novel fluctuation-induced dynamical instability influenced by dissipative effects.

Contribution

It introduces a generalized Gutzwiller approach to map the phase diagram and analyze critical behavior in open quantum systems with mixed states.

Findings

Identification of a nonequilibrium phase transition driven by competition between Hamiltonian and dissipative dynamics.

Discovery of a fluctuation-induced dynamical instability at long wavelengths.

Demonstration of dissipative renormalization effects on the system's speed of sound.

Abstract

We discuss an open driven-dissipative many-body system, in which the competition of unitary Hamiltonian and dissipative Liouvillian dynamics leads to a nonequilibrium phase transition. It shares features of a quantum phase transition in that it is interaction driven, and of a classical phase transition, in that the ordered phase is continuously connected to a thermal state. Within a generalized Gutzwiller approach which includes the description of mixed state density matrices, we characterize the complete phase diagram and the critical behavior at the phase transition approached as a function of time. We find a novel fluctuation induced dynamical instability, which occurs at long wavelength as a consequence of a subtle dissipative renormalization effect on the speed of sound.