Spectral properties of strongly correlated bosons in two-dimensional optical lattices

TL;DR

This paper investigates the spectral properties of the two-dimensional Bose-Hubbard model using the variational cluster approach, focusing on phase transitions and spectral functions relevant to ultracold atomic gases in optical lattices.

Contribution

It provides new calculations of the phase boundary and spectral functions for the 2D Bose-Hubbard model, comparing results across different Mott lobes.

Findings

Phase boundary of the Mott-superfluid transition calculated and compared.

Spectral functions in the first and second Mott lobes show similar intensity distributions.

Densities of states and momentum distributions are evaluated.

Abstract

Spectral properties of the two-dimensional Bose-Hubbard model, which emulates ultracold gases of atoms confined in optical lattices, are investigated by means of the variational cluster approach. The phase boundary of the quantum phase transition from Mott phase to superfluid phase is calculated and compared to recent work. Moreover the single-particle spectral functions in both the first and the second Mott lobe are presented and the corresponding densities of states and momentum distributions are evaluated. A qualitatively similar intensity distribution of the spectral weight can be observed for spectral functions in the first and the second Mott lobe.