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.

Collisionless Sound in a Uniform Two-Dimensional Bose Gas / Ota, Miki; Larcher, Fabrizio; Dalfovo, Franco; Pitaevskii, Lev; Proukakis, Nick P.; Stringari, Sandro. - In: PHYSICAL REVIEW LETTERS. - ISSN 0031-9007. - STAMPA. - 121:14(2018), p. 145302. [10.1103/PhysRevLett.121.145302]

Collisionless Sound in a Uniform Two-Dimensional Bose Gas

Ota, Miki;Larcher, Fabrizio;Dalfovo, Franco;Pitaevskii, Lev;Stringari, Sandro
2018-01-01

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.
2018
14
Ota, Miki; Larcher, Fabrizio; Dalfovo, Franco; Pitaevskii, Lev; Proukakis, Nick P.; Stringari, Sandro
Collisionless Sound in a Uniform Two-Dimensional Bose Gas / Ota, Miki; Larcher, Fabrizio; Dalfovo, Franco; Pitaevskii, Lev; Proukakis, Nick P.; Stringari, Sandro. - In: PHYSICAL REVIEW LETTERS. - ISSN 0031-9007. - STAMPA. - 121:14(2018), p. 145302. [10.1103/PhysRevLett.121.145302]
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11572/230012
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