From the superfluid to the Mott regime and back: triggering a non-trivial dynamics in an array of coupled condensates

TL;DR

This paper investigates the non-trivial dynamics of an array of Bose-Einstein condensates subjected to sudden changes in optical potential depth, revealing excitation effects, coherence loss, and the importance of timing in superfluid-Mott transition experiments.

Contribution

It models the system dynamics using the Bose-Hubbard framework and analyzes the effects of rapid potential changes on condensate coherence and correlations.

Findings

Potential jumps induce excitations in the condensate array.

Long waiting times can destroy system coherence.

System dynamics are sensitive to the timing of potential variations.

Abstract

We consider a system formed by an array of Bose-Einstein condensates trapped in a harmonic potential with a superimposed periodic optical potential. Starting from the boson field Hamiltonian, appropriate to describe dilute gas of bosonic atoms, we reformulate the system dynamics within the Bose-Hubbard model picture. Then we analyse the effective dynamics of the system when the optical potential depth is suddenly varied according to a procedure applied in many of the recent experiments on superfluid-Mott transition in Bose-Einstein condensates. Initially the condensates' array generated in a weak optical potential is assumed to be in the superfluid ground-state which is well described in terms of coherent states. At a given time, the optical potential depth is suddenly increased and, after a waiting time, it is quickly decreased so that the initial depth is restored. We compute the system-state evolution and show that the potential jump brings on an excitation of the system, incorporated in the final condensate wave functions, whose effects are analysed in terms of two-site correlation functions and of on-site population oscillations. Also we show how a too long waiting time can destroy completely the coherence of the final state making it unobservable.