Momentum distribution of an interacting Bose-Einstein condensed gas at finite temperature - art. no. 023604

We use a semiclassical two-fluid model to study the momentum distribution o f a Bose-Einstein condensed gas with repulsive interactions inside a harmon ic trap at finite temperature, with specific focus on atomic hydrogen. We g ive particular attention to the average kinetic energy, which is almost ent irely associated with the thermal cloud. A nonlinear dependence of the kine tic energy on temperature is displayed, affording a precise way to assess t he temperature of the gas. We also show that the kinetic energy increases w ith the strength of the interactions, reflecting an enhanced rate of deplet ion of the condensate with increasing temperature.