Collapses and Revivals of Collective Excitations in Trapped Bose Condensates

TL;DR

This paper develops a quantum theory for low-lying excitations in trapped Bose condensates, revealing collapse and revival phenomena caused by quantum fluctuations and mode dephasing, with implications for understanding collective mode dynamics.

Contribution

It introduces a quantum framework accounting for finite particle number effects and predicts collapse and revival of collective excitations in trapped Bose condensates.

Findings

Collapse of collective modes due to quantum fluctuations.

Prediction of long-timescale revivals of excitations.

Discussion of mode depletion via second-harmonic generation.

Abstract

We present a quantum theory of low-lying excitations in a trapped Bose condensate with finite particle numbers. We find that even at zero temperature condensate number fluctuations and/or fluctuations of the excitation frequency due to quantum uncertainties of the mode occupation lead to a collapse of the collective modes due to dephasing. Coherent revivals of the collective excitations are predicted on a much longer timescale. Depletion of collective modes due to second-harmonic generation is discussed.