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arXiv · 1804.04032

Collisionless sound in a uniform two-dimensional Bose gas

Miki Ota·Fabrizio Larcher·Franco Dalfovo·Lev Pitaevskii·Nikolaos P. Proukakis·Sandro Stringari
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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. Our analysis points 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.

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Miki Ota, Fabrizio Larcher, Franco Dalfovo, Lev Pitaevskii, Nikolaos P. Proukakis, Sandro Stringari. 2018-04-11. Collisionless sound in a uniform two-dimensional Bose gas. https://doi.org/10.1103/physrevlett.121.145302

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