Loading ultracold atoms onto nonlinear Bloch states and soliton states in bichromatic lattices

TL;DR

This paper proposes a numerical method to load ultracold atoms onto nonlinear Bloch and soliton states in a bichromatic lattice, analyzing the process and stability for experimental realization.

Contribution

It introduces a specific standing wave-pulse sequence for loading atoms onto inverted bands and producing solitons, with analysis of external potential effects and instabilities.

Findings

Identified a suitable pulse sequence for loading atoms onto inverted bands.

Demonstrated formation of soliton solutions via numerical simulations.

Analyzed the impact of external potentials and dynamical instabilities.

Abstract

We simulate and analyze an experimental method of loading interacting ultracold atoms onto nontrivial quantum states such as nonlinear Bloch wave and soliton solutions in a 1-dimensional bichromatic lattice. Of standard bands, inverted bands, and bands with Dirac-like points permitted by a bichromatic lattice, we consider the case of an inverted band and examine the loading process in terms of nonlinear Bloch waves formed by an aggregate of ultracold atoms described by the mean-field model. Specifically, we solved the Gross-Pitaevskii equation numerically and found an appropriate standing wave-pulse sequence for the inverted band, which sequence proved to be a suitable protocol for producing soliton solutions. In addition, we examined the effect of an external potential and dynamical instabilities for the post-loading process. We also provide an appropriate data set for future experimental realization of our findings.