Quantum states of p-band bosons in optical lattices

TL;DR

This paper investigates the phase behavior of repulsive bosons in the first excited p-band of optical lattices using mean-field and Gutzwiller methods, revealing detailed phase diagrams and the rapid applicability of mean-field theory.

Contribution

It provides the first detailed phase diagrams and characterization of Mott states for p-band bosons in optical lattices, including the comparison of mean-field and Gutzwiller approaches.

Findings

Mean-field theory becomes accurate after the Mott-superfluid transition.

Detailed phase diagrams for 2D and 3D p-band bosons are presented.

First Mott-states are characterized in detail.

Abstract

We study a gas of repulsively interacting bosons in the first excited band of an optical lattice. We explore this p-band physics both within the framework of a standard mean-field theory as well as with the more accurate generalized Gutzwiller ansatz. We find the phase diagrams for two- and three-dimensional systems and characterize the first Mott-states in detail. Furthermore, we find that even though the p-band model has strongly anisotropic kinetic energies and inter-flavor interaction terms are missing in the lowest band theory, the mean-field theory becomes useful quite rapidly once the transition from the Mott-insulator to the superfluid is crossed.