Beliaev damping of quasi-particles in a Bose-Einstein condensate

TL;DR

This paper experimentally investigates Beliaev damping of quasi-particles in a Bose-Einstein condensate, revealing suppression of collisions at low momentum and employing hydrodynamic simulations to validate the analysis.

Contribution

It provides the first measurement of Beliaev damping suppression in a BEC at low momentum, exploring the continuous quasi-particle energy spectrum regime.

Findings

Collision suppression observed at low quasi-particle momentum

Hydrodynamic simulations confirm damping cross-section assumptions

First experimental evidence in this unexplored regime

Abstract

We report a measurement of the suppression of collisions of quasi-particles with ground state atoms within a Bose-Einstein condensate at low momentum. These collisions correspond to Beliaev damping of the excitations, in the previously unexplored regime of the continuous quasi-particle energy spectrum. We use a hydrodynamic simulation of the expansion dynamics, with the Beliaev damping cross-section, in order to confirm the assumptions of our analysis.