Multiband bosons in optical lattices

TL;DR

This paper investigates how including higher energy bands in optical lattice models alters the behavior of bosonic gases, revealing phenomena like reentrant superfluidity and modified Mott insulator phases.

Contribution

It introduces a generalized Gutzwiller approach to incorporate first excited bands, extending the standard Bose-Hubbard model for more accurate predictions.

Findings

Reentrant superfluidity predicted beyond the lowest band model

Decreased Mott lobes width at strong coupling

Modification of phase diagram due to higher bands

Abstract

We study a gas of repulsively interacting bosons in an optical lattice and explore the physics beyond the lowest band Hubbard model. Utilizing a generalized Gutzwiller ansatz, we find how the lowest band physics is modified by the inclusion of the first excited bands. In contrast to the prediction of the lowest band Bose-Hubbard model, a reentrant behavior of superfluidity is envisaged as well as decreasing width of the Mott lobes at strong coupling.