An Investigation of Mean-field Effects for a Bose Condensate in an Optical Lattice

TL;DR

This study uses three-dimensional mean-field simulations to analyze Bose-Einstein condensate behavior in optical lattices, revealing the importance of non-adiabatic effects and transverse-longitudinal coupling in experimental outcomes.

Contribution

It demonstrates that full 3D GPE simulations are essential to accurately model experimental results, highlighting the limitations of 1D approximations in optical lattice studies.

Findings

Non-adiabatic loading reproduces experimental phenomena

Transverse-longitudinal coupling affects condensate dynamics

1D models are insufficient for accurate predictions

Abstract

This paper presents a mean-field numerical analysis, using the full three-dimensional time-dependent Gross-Pitaevskii equation (GPE), of an experiment carried out by Orzel et al. [Science 291, 2386 (2001)] intended to show number squeezing in a gaseous Bose-Einstein condensate in an optical lattice. The motivation for the present work is to elucidate the role of mean-field effects in understanding the experimental results of this work and those of related experiments. We show that the non-adiabatic loading of atoms into optical lattices reproduces many of the main results of the Orzel et al. experiment, including both loss of interference patterns as laser intensity is increased and their regeneration when intensities are lowered. The non-adiabaticity found in the GPE simulations manifests itself primarily in a coupling between the transverse and longitudinal dynamics, indicating that one-dimensional approximations are inadequate to model the experiment.