Phase diagram of disordered Bose-Hubbard model based on mean-field and percolation analysis in two dimensions and at fixed $n=1$ filling

TL;DR

This paper maps the phase diagram of the disordered Bose-Hubbard model in two dimensions at fixed filling, revealing re-entrant superfluid phases and analyzing the transition as a percolation process using mean-field theory.

Contribution

It provides a mean-field based phase diagram showing re-entrant superfluidity and interprets the phase transition as a percolation transition, extending previous quantum Monte Carlo findings.

Findings

Re-entrant superfluid phase observed between Bose-glass phases.

Phase transition characterized as a percolation transition.

Robustness of the re-entrant superfluid confirmed.

Abstract

We present a phase diagram of Bose-Hubbard model with on-site chemical potential disorder at two dimensions within the scope of mean-field theory. The phase diagram in the disorder strength ($\Delta$) and the on-site repulsion ($U$) for disordered BHM at fixed filling $\langle{n\rangle}=1$, show interesting re-entrance of superfluid phase, sandwiched between Bose-glass phases, as observed by the previous QMC results. We probe the Bose-glass to superfluid transition, as a percolation transition, based on the mean-field results at various parts of the phase diagram using both $\Delta$ and $U$ as the tuning parameter. We argue the robustness of the re-entrant superfluid.