Effect of quantum fluctuations on the dipolar motion of Bose-Einstein condensates in optical lattices

TL;DR

This paper investigates how quantum fluctuations influence the dipolar motion of Bose-Einstein condensates in optical lattices, revealing damping effects and a crossover between classical chaos and quantum phase transition.

Contribution

It incorporates quantum fluctuations into the analysis of condensate dynamics, extending mean-field results to include damping and crossover phenomena.

Findings

Quantum fluctuations cause damping of condensate oscillations.

A smooth crossover exists between classical chaos and quantum phase transition.

Nontrivial dynamical effects in density fluctuations and coherence are observed.

Abstract

We revisit dipolar motion of condensate atoms in one-dimensional optical lattices and harmonic magnetic traps including quantum fluctuations within the truncated Wigner approximation. In the strong tunneling limit we reproduce the meanfield results with a sharp dynamical transition at the critical displacement. When the tunneling is reduced, on the contrary, strong quantum fluctuations lead to finite damping of condensate oscillations even at infinitesimal displacement. We argue that there is a smooth crossover between the chaotic classical transition at finite displacement and the superfluid-to-insulator phase transition at zero displacement. We further analyze the time dependence of the density fluctuations and of the coherence of the condensate and find several nontrivial dynamical effects, which can be observed in the present experimental conditions.