Temps de coh érence d'un condensat de Bose–Einstein dans un gaz isolé harmoniquement piégé

Publication date: Available online 7 May 2018 Source:Comptes Rendus Physique Author(s): Yvan Castin, Alice Sinatra We study the condensate phase dynamics in a low-temperature equilibrium gas of weakly interacting bosons, harmonically trapped and isolated from the environment. We find that at long times, much longer than the collision time between Bogoliubov quasi-particles, the variance of the phase accumulated by the condensate grows with a ballistic term quadratic in time and a diffusive term affine in time. We give the corresponding analytical expressions in the limit of a large system, in the collisionless regime and in the ergodic approximation for the quasi-particle motion. When properly rescaled, they are described by universal functions of the temperature divided by the Thomas–Fermi chemical potential. The same conclusion holds for the mode damping rates. Such universality class differs from the previously studied one of the homogeneous gas.
Source: Comptes Rendus Physique - Category: Physics Source Type: research