Localization induced by spatially uncorrelated subohmic baths in one dimension

TL;DR

This paper investigates how spatially uncorrelated subohmic baths induce localization in a one-dimensional XXZ spin chain, leading to a phase transition and insulating behavior without gap opening, highlighting bath-induced fractional excitations.

Contribution

It reveals a novel bath-induced localization mechanism causing a phase transition and insulating state in a 1D spin chain without traditional gap formation.

Findings

Transition from Luttinger liquid to SDW phase with increasing bath coupling

Emergence of SDW without gap opening due to fractional excitations

System becomes insulating as shown by DC conductivity measurements

Abstract

We study an incommensurate XXZ spin chain coupled to a collection of local harmonic baths. At zero temperature, by varying the strength of the coupling to the bath the chain undergoes a quantum phase transition between a Luttinger liquid phase and a spin density wave (SDW). As opposed to the standard mechanism, the SDW emerges in the absence of the opening of a gap, but it is due to ``fractional excitations" induced by the bath. We also show, by computing the DC conductivity, that the system is insulating in the presence of a subohmic bath. We interpret this phenomenon as localization induced by the bath \`a la Caldeira and Leggett.