We find that non-equilibrium boundary conditions generically trigger long range order in non-equilibrium steady states of locally but strongly interacting quantum chains. We treated models quantum spin 1/2 chains which are driven far from equilibrium by coupling to a pair Lindblad reservoirs attached to the ends of the chain. In particular, we find a phase transition from exponentially decaying to long range spin-spin correlations in integrable Heisenberg XXZ chain by changing the anisotropy parameter. Long range order also typically emerges after breaking the integrability of the model.
COBISS.SI-ID: 2262884
We study a new class of quantum chaotic systems with dynamical localization, where gain/loss mechanisms break the Hermiticity, while allowing for parity-time (PT) symmetry. For a value gamma_PT of the gain/loss parameter the spectrum undergoes a spontaneous phase transition from real (exact phase) to complex values (broken phase). We develop a one parameter scaling theory for gamma_PT, and show that chaos assists the exact PT-phase. Our results have applications to the design of active optical elements with PT-symmetry.
COBISS.SI-ID: 2234724