Markovian dissipation can stabilize a (localization) quantum phase transition

TL;DR

This paper demonstrates that Markovian dissipation can stabilize a quantum phase transition in a driven open quantum system, leading to a localization transition where the steady state becomes pure and exhibits quantum properties.

Contribution

It introduces a novel quantum phase transition stabilized by Markovian dissipation in a spin-boson model with driven dynamics and frequency-dependent loss.

Findings

Steady state exhibits a localization phase transition.

Transition occurs when the steady state becomes pure.

Quantum behavior emerges in a dynamical steady state.

Abstract

Quantum phase transitions are a cornerstone of many-body physics at low temperatures but have remained elusive far from equilibrium. Driven open quantum systems -- a prominent non-equilibrium platform where coherent dynamics competes with Markovian dissipation from the environment -- often exhibit an effective classical behavior. In this work, we present a nontrivial quantum phase transition that is stabilized, rather than destroyed, by Markovian dissipation. We consider a variant of the paradigmatic spin-boson model where the spin is driven and bosons are subject to Markovian loss proportional to frequency (hence, vanishing at low frequencies). We show that the steady state exhibits a localization phase transition where the spin's dynamics is frozen, to be contrasted with the ground-state transition in the absence of dissipation. Furthermore, this transition occurs when the steady state becomes pure. The latter is not simply a dark state of dissipation but rather emerges from a nontrivial renormalization of the spin dynamics by low-frequency bosonic modes. Our work provides a nontrivial example where quantumness, typically reserved for ground states, also emerges in dynamical settings, with potential applications in quantum computation.