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Finite-Temperature Collective Excitation of a Bose-Einstein Condensate

Maxim Olshanii
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Abstract

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.

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Maxim Olshanii. 1998-07-31. Finite-Temperature Collective Excitation of a Bose-Einstein Condensate. https://arxiv.org/abs/cond-mat/9807412

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