Entropy production within a pulsed Bose-Einstein condensate

TL;DR

This paper predicts that sinusoidal forcing of a Bose-Einstein condensate can cause a transition from adiabatic to chaotic dynamics, leading to coherence loss and heating, with implications for experimental control.

Contribution

It introduces a scenario linking coherence loss in BECs to the breakdown of adiabatic invariants under sinusoidal forcing, supported by a two-site model analysis.

Findings

Coherence remains high under weak forcing, indicating adiabatic behavior.

Exceeding a critical forcing amplitude causes a sharp coherence drop.

Loss of adiabatic invariants correlates with the onset of chaos and heating.

Abstract

We suggest to subject anharmonically trapped Bose-Einstein condensates to sinusoidal forcing with a smooth, slowly changing envelope, and to measure the coherence of the system after such pulses. In a series of measurements with successively increased maximum forcing strength one then expects an adiabatic return of the condensate to its initial state as long as the pulses remain sufficiently weak. In contrast, once the maximum driving amplitude exceeds a certain critical value there should be a drastic loss of coherence, reflecting significant heating induced by the pulse. This predicted experimental signature is traced to the loss of an effective adiabatic invariant, and to the ensuing breakdown of adiabatic motion of the system's Floquet state when the many-body dynamics become chaotic. Our scenario is illustrated with the help of a two-site model of a forced bosonic Josephson junction, but should also hold for other, experimentally accessible configurations.