Impurity Scattering in a Bose-Einstein Condensate at finite temperature

TL;DR

This paper investigates how finite temperature affects impurity atom scattering in a Bose-Einstein condensate, revealing temperature-dependent scattering rates and energy exchange processes, with implications for experimental observations.

Contribution

It provides a detailed analysis of impurity scattering at finite temperature, highlighting the role of thermal atoms and velocity thresholds in energy exchange.

Findings

Scattering rate increases with temperature due to thermal atoms.

Below Landau velocity, collisions cool the condensate.

Above critical velocity, dissipative collisions dominate.

Abstract

We consider the effects of finite temperature on the scattering of impurity atoms in a BoseEinstein condensate, showing that the scattering rate is enhanced by the thermal atoms. Collisions can increase or decrease the impurity energy. Below the Landau velocity only the first process occurs, i.e., the collisions cool the condensate. Above the critical velocity the dissipative collisions prevail over the cooling ones for sufficiently low temperatures. These considerations are applied to a recent experiment.