The Influence of s-wave interactions on focussing of atoms

TL;DR

This paper investigates how s-wave interactions affect the focusing of a rubidium Bose-Einstein condensate using an optical lattice, combining numerical simulations and classical models to predict achievable focus sizes.

Contribution

It introduces a modified classical trajectory model that accounts for interactions, improving predictions of focus size in Bose-Einstein condensate focusing.

Findings

Classical trajectory model underestimates focus width without interactions.

Including interactions in the model yields accurate focus size estimates.

Focusing of around 20 nm is possible in strongly interacting condensates.

Abstract

The focusing of a rubidium Bose-Einstein condensate via an optical lattice potential is numerically investigated. The results are compared with a classical trajectory model which under-estimates the full width half maximum of the focused beam. Via the inclusion of the effects of interactions, in the Bose-Einstein condensate, into the classical trajectory model we show that it is possible to obtain reliable estimates for the full width half maximum of the focused beam when compared to numerical integration of the Gross-Pitaevskii equation. Finally, we investigate the optimal regimes for focusing and find that for a strongly interacting Bose-Einstein condensate focusing of order 20 nm may be possible.