Superfluid - Bose-Glass Transition in Weakly Disordered Commensurate One-Dimensional System

TL;DR

This paper investigates how weak disorder influences the superfluid to Bose-glass transition in a one-dimensional system with integer filling, revealing that disorder can restore superfluidity from a Mott insulator and that superfluid and Mott insulator phases are separated by a Bose-glass phase at any disorder level.

Contribution

The study provides an explicit renormalization-group analysis showing the disorder strength needed to induce superfluidity from a Mott insulator is larger than that to create a Bose-glass from the Mott insulator.

Findings

Disorder can restore superfluidity from Mott insulator.

Superfluid and Mott insulator phases are separated by Bose-glass at any disorder level.

Explicit phase boundary equation derived for the superfluid-Bose-glass transition.

Abstract

We study the effect of commensurability (integer filling factor) on the superfluid (SF) - Bose-glass (BG) transition in a one-dimensional disordered system in the limit of weak disorder, when the effect is most pronounced and, on the other hand, may be traced via the renormalization-group analysis. The equation for the SF-BG phase boundary demonstrating the effect of disorder-stimulated superfluidity implies that the strength of disorder sufficient to restore superfluidity from Mott insulator (MI) is much larger than that enough to turn MI into BG. Thus we provide an explicit proof of the fact that at arbitrarily small disorder the SF and MI phases are always separated by BG.