Excitations in disordered bosonic optical lattices

TL;DR

This paper investigates how disorder affects spectral excitations in ultracold bosonic gases in optical lattices, revealing the impact of disorder distribution shape and strength on spectral properties using the variational cluster approach.

Contribution

It introduces a detailed analysis of spectral excitations considering various disorder distributions in the Bose-Hubbard model, providing insights into experimental observables.

Findings

Spectral spectra strongly depend on disorder distribution shape and strength.

The Mott gap varies with disorder, with differences between formal and experimental measures.

Disorder influences the spectral features in a manner relevant for experimental detection.

Abstract

Spectral excitations of ultracold gases of bosonic atoms trapped in one dimensional optical lattices with disorder are investigated by means of the variational cluster approach applied to the Bose-Hubbard model. In particular, qualitatively different disorder distributions typically employed in experiments are considered. The computed spectra exhibit a strong dependence on both the shape of the disorder distribution and the disorder strength. We compare alternative results for the Mott gap obtained from its formal definition and from the minimum peak distance, which is the quantity available from experiments.