title: Dynamical phase transitions and instabilities in open atomic many-body systems.
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. We characterize the 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.
authors.affiliation: Institute for Theoretical Physics, University of Innsbruck, Technikerstrasse 25, A-6020 Innsbruck, Austria.
authors.forename: Sebastian
authors.initials: S
authors.lastname: Diehl
authors.forename: Andrea
authors.initials: A
authors.lastname: Tomadin
authors.forename: Andrea
authors.initials: A
authors.lastname: Micheli
authors.forename: Rosario
authors.initials: R
authors.lastname: Fazio
authors.forename: Peter
authors.initials: P
authors.lastname: Zoller