Mean-field phase diagram for Bose-Hubbard Hamiltonians with random hopping

TL;DR

This paper maps out the phase diagram of disordered Bose-Hubbard models with random hopping using a mean-field approach, revealing phases like Mott insulator, superfluid, and Bose-glass, and connecting phase boundaries to an Anderson model.

Contribution

It introduces a mean-field scheme for the Bose-Hubbard Hamiltonian with random hopping, extending understanding of disorder effects in ultracold bosons.

Findings

Disorder induces a Bose-glass phase similar to that with random on-site potential.

Phase boundaries relate to an off-diagonal Anderson model.

The phase diagram includes Mott insulator, superfluid, and Bose-glass regions.

Abstract

The zero-temperature phase diagram for ultracold Bosons in a random 1D potential is obtained through a site-decoupling mean-field scheme performed over a Bose-Hubbard (BH) Hamiltonian whose hopping term is considered as a random variable. As for the model with random on-site potential, the presence of disorder leads to the appearance of a Bose-glass phase. The different phases -i.e. Mott insulator, superfluid, Bose-glass- are characterized in terms of condensate fraction and superfluid fraction. Furthermore, the boundary of the Mott lobes are related to an off-diagonal Anderson model featuring the same disorder distribution as the original BH Hamiltonian.