Eur. Phys. J. D 25, 167-171 (2003)
https://doi.org/10.1140/epjd/e2003-00204-8

Castaing's instability in a trapped ultra-cold gas

Laboratoire Kastler Brossel, Département de Physique de l'ENS, 24 rue Lhomond, 75005 Paris, France

Corresponding authors: ^a fuchs@lkb.ens.fr - ^b olivier.prevote@voila.fr - ^c gangardt@lkb.ens.fr

Received: 1 October 2002
Published online: 15 July 2003

Abstract

We consider a trapped ultra-cold gas of (non-condensed) bosons with two internal states (described by a pseudo spin) and study the stability of a longitudinal pseudo spin polarization gradient. For this purpose, we numerically solve a kinetic equation corresponding to a situation close to the experiment at JILA [1]. It shows the presence of Castaing's instability of transverse spin polarization fluctuations at long wavelengths. This phenomenon could be used to create spontaneous transverse spin waves.