We consider the effects of finite temperature on the scattering of impurity atoms in a Bose-Einstein 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.
Physical Review A
- Pub Date:
- August 2002
- Scattering of atoms and molecules;
- Other topics in quantum fluids and solids;
- liquid and solid helium;
- Condensed Matter - Quantum Gases
- 4 figures.