Finite-Temperature Collective Excitation of a Bose-Einstein Condensate
Abstract
Description
We derive a simple formula for the finite-temperature shifts of the collective excitations of a Bose-Einstein condensate. To test the validity of our treatment we apply it to explain the anomalous behavior of the ``m=2'' excitation frequency in the recent JILA experiments (D. S. Jin et al, PRL, 78 (1997) 764), where this frequency does not approach its ``noninteracting'' value at $ω= 2 ω_ρ$ but, instead, decreases with temperature. It turns out that the effect is mainly governed by a resonance between the condensate excitation frequency and one of the quantum eigenfrequencies of the thermal cloud. Comparison of our predictions with the JILA experimental data shows a good agreement.
4 pages, 1 figure, RevTex & PostScript
4 pages, 1 figure, RevTex & PostScript