Parametric pair production of collective excitations in a Bose-Einstein condensate

TL;DR

This paper demonstrates parametric generation of collective excitations in a Bose-Einstein condensate through transverse mode excitation, confirming theoretical predictions and exploring early dynamics and pair correlations.

Contribution

It provides experimental validation of Bogoliubov theory in describing pairwise collective excitation production in elongated Bose-Einstein condensates.

Findings

Experimental growth rate matches theoretical predictions.

Confirmed small quasiparticle interactions in elongated condensates.

Observed oscillations linked to pair correlations and interaction dynamics.

Abstract

By exciting the transverse breathing mode of an elongated Bose-Einstein condensate, we parametrically produce longitudinal collective excitations in a pairwise manner. This process also referred to as Faraday wave generation, can be seen as an analog to cosmological particle production. Building upon single particle detection, we investigate the early time dynamics of the exponential growth and compare our observations with a Bogoliubov description. The growth rate we observe experimentally is in very good agreement with theoretical predictions, demonstrating the validity of the Bogoliubov description and thereby confirming the smallness of quasiparticle interactions in such an elongated gas. We also discuss the presence of oscillations in the atom number, which are due to pair correlations and to the rate at which interactions are switched off.