Quantum phase transition in a far from equilibrium steady state of XY spin chain

TL;DR

This paper investigates a quantum phase transition in a non-equilibrium steady state of an open XY spin chain, revealing a transition from saturation to linear growth in correlations and entanglement entropy.

Contribution

It introduces a novel method to compute the non-equilibrium steady state of an open XY spin chain and demonstrates a quantum phase transition with long-range order.

Findings

Evidence of a quantum phase transition characterized by long-range order.

Transition from saturation to linear growth in spin-spin correlations.

Entanglement entropy shifts from saturation to linear growth with system size.

Abstract

Using quantization in the Fock space of operators we compute the non-equilibrium steady state in an open Heisenberg XY spin 1/2 chain of finite but large size coupled to Markovian baths at its ends. Numerical and theoretical evidence is given for a far from equilibrium quantum phase transition with spontaneous emergence of long-range order in spin-spin correlation functions, characterized by a transition from saturation to linear growth with the size of the entanglement entropy in operator space.