Odd Bose condensation in steady states far from equilibrium

Bose-Einstein condensation, the macroscopic occupation of a single quantum state, appears in equilibrium quantum statistical mechanics. We show that even when a degenerate Bose gas is driven into a steady state far from equilibrium, e.g. by time-periodic driving, Bose-Einstein condensation survives in a generalized form [1]: the unambiguous selection of an odd number of states acquiring large occupations.

We study the effect in driven-dissipative model systems, including tight-binding chains. We find anomalously long-range order in one dimension and propose a quantum switch for heat conductivity based on shifting between one and three Bose selected states.

[1] Vorberg, Wustmann, Ketzmerick, Eckardt, PRL 111, 240405 (2013)