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arXiv:1804.04032 · Physical Review Letters

Collisionless Sound in a Uniform Two-Dimensional Bose Gas

Miki Ota, F. Larcher, F. Dalfovo, Лев П. Питаевский, Nick P. Proukakis, S. Stringari

Published Oct 3, 2018• 49 citations
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Abstract

Using linear response theory within the random phase approximation, we investigate the propagation of sound in a uniform two dimensional (2D) Bose gas in the collisionless regime. We show that the sudden removal of a static density perturbation produces a damped oscillatory behavior revealing that sound can propagate also in the absence of collisions, due to mean-field interaction effects. We provide explicit results for the sound velocity and damping as a function of temperature, pointing out the crucial role played by Landau damping. We support our predictions by performing numerical simulations with the stochastic (projected) Gross-Pitaevskii equation. The results are consistent with the recent experimental observation of sound in a weakly interacting 2D Bose gas both below and above the superfluid Berezinskii-Kosterlitz-Thouless transition.

DOI
10.1103/physrevlett.121.145302

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