Quantum Monte Carlo simulations for the Bose-Hubbard model with random chemical potential; localized Bose-Einstein condensation without superfluidity

TL;DR

This study uses quantum Monte Carlo simulations to explore the hardcore Bose-Hubbard model with random chemical potential, revealing a localized Bose-Einstein condensate phase without superfluidity under correlated disorder.

Contribution

It introduces the analysis of correlated disorder in the Bose-Hubbard model and identifies a localized condensate phase distinct from superfluid and normal states.

Findings

Correlated disorder leads to a localized condensate state.

Superfluid density diminishes with disorder, but localized condensation persists.

Distinct phases are identified based on temperature and disorder type.

Abstract

The hardcore-Bose-Hubbard model with random chemical potential is investigated using quantum Monte Carlo simulation. We consider two cases of random distribution of the chemical potential: a uniformly random distribution and a correlated distribution. The temperature dependences of the superfluid density, the specific heat, and the correlation functions are calculated. If the distribution of the randomness is correlated, there exists an intermediate state, which can be thought of as a localized condensate state of bosons, between the superfluid state and the normal state.