Long range order in non-equilibrium interacting quantum spin chains

TL;DR

This paper demonstrates that non-equilibrium boundary conditions can induce long-range order in quantum spin chains, with phase transitions observed via large-scale simulations, highlighting the impact of boundary driving and integrability on correlation properties.

Contribution

It provides the first large-scale numerical evidence that non-equilibrium boundary conditions can generate long-range order in quantum spin chains, including phase transitions related to anisotropy and integrability.

Findings

Long-range order emerges under non-equilibrium boundary conditions.

A phase transition occurs from exponential decay to long-range correlations.

Breaking integrability also promotes long-range order.

Abstract

We conjecture that non-equilibrium boundary conditions generically trigger long range order in non-equilibrium steady states of locally interacting quantum chains. Our result is based on large scale density matrix renormalization group simulations of several models of quantum spin 1/2 chains which are driven far from equilibrium by coupling to a pair of unequal Lindblad reservoirs attached locally 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.