Bose-Hubbard model with random impurities: Multiband and nonlinear hopping effects

TL;DR

This paper explores how multiband and nonlinear hopping effects influence the phase diagrams of bosonic atoms in disordered lattices, revealing the disappearance of triple points with hopping disorder.

Contribution

It introduces a model with site-dependent hopping effects and compares phase diagrams using multiple methods, highlighting the impact of hopping disorder.

Findings

Triple points exist in chemical-potential disorder models.

Hopping disorder causes triple points to vanish.

Multiband and nonlinear effects modify phase boundaries.

Abstract

We investigate the phase diagrams of theoretical models describing bosonic atoms in a lattice in the presence of randomly localized impurities. By including multiband and nonlinear hopping effects we enrich the standard model containing only the chemical-potential disorder with the site-dependent hopping term. We compare the extension of the MI and the BG phase in both models using a combination of the local mean-field method and a Hartree-Fock-like procedure, as well as, the Gutzwiller-ansatz approach. We show analytical argument for the presence of triple points in the phase diagram of the model with chemical-potential disorder. These triple points however, cease to exists after the addition of the hopping disorder.