Superfluid stiffness of a driven dissipative condensate with disorder.
Observations of macroscopic quantum coherence in driven systems, e.g. polariton condensates, have strongly stimulated experimental as well as theoretical efforts during the last decade. We address the question of whether a driven quantum condensate is a superfluid, allowing for the effects of disorder and its nonequilibrium nature. We predict that for spatial dimensions d<4 the superfluid stiffness vanishes once the condensate exceeds a critical size, and treat in detail the case d=2. Thus a nonequilibrium condensate is not a superfluid in the thermodynamic limit, even for weak disorder, although superfluid behavior would persist in small systems.
Institut für Theoretische Physik, Universität Leipzig, 04009 Leipzig, Germany.
Alexander
A
Janot
Instituut-Lorentz, Universiteit Leiden, P.O. Box 9506, 2300 RA Leiden, Netherlands.
Timo
T
Hyart
School of Physics and CRANN, Trinity College, Dublin 2, Ireland.
Paul R
PR
Eastham
Institut für Theoretische Physik, Universität Leipzig, 04009 Leipzig, Germany.
Bernd
B
Rosenow