Mean-field phase diagram of cold lattice bosons in disordered potentials

TL;DR

This paper uses a site-dependent mean-field approach to map out the phase diagram of disordered cold lattice bosons, identifying superfluid, Mott insulator, Bose-glass, and normal fluid phases and relating phase boundaries to Anderson model spectral features.

Contribution

It introduces a mean-field method that effectively captures quantum phases in the disordered Bose-Hubbard model, linking phase boundaries to Anderson localization properties.

Findings

Identifies phase boundaries using superfluid and condensate fractions.

Relates Mott lobe boundaries to spectral features of Anderson model.

Characterizes phases by compressibility and superfluidity.

Abstract

We show that a site-dependent mean-field approach captures the quantum phases of the disordered Bose-Hubbard model commonly adopted to describe ultracold bosons in random optical lattice potentials. The different phases, namely superfluid, Mott insulator, Bose-glass and -- at finite temperature -- normal fluid, are characterized by means of the superfluid and condensate fractions, and compressibility of the system. We point out that both the boundaries of the Mott lobes and the nature of the phase surrounding them are related to the spectral features of a purely off-diagonal non-interacting Anderson model. We compare our results to other works.