Recent experimental developments in diverse areas - ranging from cold atomic
gases over light-driven semiconductors to microcavity arrays - move systems
into the focus, which are located on the interface of quantum optics, many-body
physics and statistical mechanics. They share in common that coherent and
driven-dissipative quantum dynamics occur on an equal footing, creating
scenarios without immediate counterpart in condensed matter. A key challenge
is to identify universal macroscopic phenomena, which manifestly witness
microscopic non-equilibrium conditions.
Here, we will report on three results in this direction. First, we show that
dynamical Bose criticality in driven systems lies beyond the equilibrium Halperin-
Hohenberg classification. Second, we argue that driven open systems in two
dimensions, realized by ensembles of exciton-polaritons, cannot support
superfluidity and quasi-long range order. Third, we reveal new, manifestly non-
equilibrium scaling behavior in the short time heating dynamics of interacting,
ultracold atomic quantum wires.