Multi-orbital bosons in bipartite optical lattices

TL;DR

This paper investigates the behavior of interacting bosons in a bipartite optical lattice, deriving a three orbital tight-binding and Bose-Hubbard model to explore how hybridization affects phase diagrams and condensate formation.

Contribution

It introduces a novel three orbital tight-binding and Bose-Hubbard model for nearly degenerate excited bands in bipartite optical lattices, revealing hybridization effects on phases.

Findings

Hybridization influences phase diagrams significantly.

Condensed phases can appear within Mott insulating regions due to hybridization.

Trap effects enable coexistence of different phases.

Abstract

We study interacting bosons in a two dimensional bipartite optical lattice. By focusing on the regime where the first three excited bands are nearly degenerate we derive a three orbital tight-binding model which captures the most relevant features of the bandstructure. In addition, we also derive a corresponding generalized Bose-Hubbard model and solve it numerically under different situations, both with and without a confining trap. It is especially found that the hybridization between sublattices can strongly influence the phase diagrams and in a trap enable even appearances of condensed phases intersecting the same Mott insulating plateaus.