Bose-Einstein condensates on tilted lattices: coherent, chaotic and subdiffusive dynamics

TL;DR

This paper investigates the complex dynamics of Bose-Einstein condensates in tilted optical lattices, revealing localized states, coherent oscillations, irregular behavior, and subdiffusive spreading depending on the strength of the static field.

Contribution

It provides a comprehensive analysis of the dynamical regimes of BECs in tilted lattices using a discrete mean-field approach, highlighting new localized and subdiffusive phenomena.

Findings

Existence of non-spreading localized states at strong fields

Observation of coherent Bloch oscillations with fractional revivals

Identification of subdiffusive wave-packet spreading with t^{1/4}

Abstract

The dynamics of a (quasi)one-dimensional interacting atomic Bose-Einstein condensate in a tilted optical lattice is studied in a discrete mean-field approximation, i.e., in terms of the discrete nonlinear Schr\"odinger equation. If the static field is varied the system shows a plethora of dynamical phenomena. In the strong field limit we demonstrate the existence of (almost) non-spreading states which remain localized on the lattice region populated initially and show coherent Bloch oscillations with fractional revivals in the momentum space (so called quantum carpets). With decreasing field, the dynamics becomes irregular, however, still confined in configuration space. For even weaker fields we find sub-diffusive dynamics with a wave-packet width spreading as $t^{1/4}$.