Phase Diagram of Commensurate Two-Dimensional Disordered Bose Hubbard Model

TL;DR

This study maps the complete phase diagram of the disordered two-dimensional Bose-Hubbard model at unity filling, revealing persistent superfluid regions with low transition temperatures and weak disorder sensitivity near the superfluid-insulator transition.

Contribution

It provides the first comprehensive quantum Monte Carlo analysis of the full phase diagram for this model, highlighting the robustness of superfluid phases against disorder.

Findings

Superfluid regions extend up to high disorder and interaction strengths.

Superfluid fractions are small, leading to low transition temperatures.

Weak disorder has minimal impact near the superfluid-insulator transition.

Abstract

We establish the full groundstate phase diagram of disordered Bose-Hubbard model in two-dimensions at unity filling factor via quantum Monte Carlo simulations. Similarly to the three-dimensional case we observe extended superfluid regions persisting up to extremely large values of disorder and interaction strength which, however, have small superfluid fractions and thus low transition temperatures. In the vicinity of the superfluid--insulator transition of the pure system, we observe an unexpectedly weak---almost not resolvable---sensitivity of the critical interaction to the strength of (weak) disorder.