Disorder-induced superfluidity

TL;DR

This study uses quantum Monte Carlo simulations to explore how disorder affects the phases of hard-core bosons with attractive interactions, revealing a disorder-stabilized superfluid phase and transitions to insulating phases.

Contribution

It demonstrates that moderate disorder can induce a superfluid phase in a system that would otherwise be a Mott insulator without disorder.

Findings

Disorder stabilizes a glassy superfluid phase.

Transition to Bose glass occurs with increased disorder or interactions.

Superfluid phase exists within a specific range of attractive interactions.

Abstract

We use quantum Monte Carlo simulations to study the phase diagram of hard-core bosons with short-ranged {\it attractive} interactions, in the presence of uniform diagonal disorder. It is shown that moderate disorder stabilizes a glassy superfluid phase in a range of values of the attractive interaction for which the system is a Mott insulator, in the absence of disorder. A transition to an insulating Bose glass phase occurs as the strength of the disorder or interactions increases.