Fizika Nizkikh Temperatur: Volume 46, Number 5 (May 2020), p. 572-577    ( to contents , go back )

Counterflow in Bose gas bilayers: collective modes and dissipationless drag

Saeed H. Abedinpour

Department of Physics, Institute for Advanced Studies in Basic Sciences (IASBS), Zanjan 45137-66731, Iran
School of Nano Science, Institute for Research in Fundamental Sciences (IPM), Tehran 19395-5531, Iran

B. Tanatar

Department of Physics, Bilkent University, Ankara 06800, Turkey
E-mail: tanatar@fen.bilkent.edu.tr

Received December 3, 2019, published online March 24, 2020

Abstract

We investigate the collective density oscillations and dissipationless drag effect in bilayer structures of ultracold bosons in the presence of counterflow. We consider different types of inter-particle interactions and obtain the drag coefficient and effect of counterflow on the sound velocity. We observe that counterflow enhances (suppresses) the energy of symmetric (asymmetric) density mode and drives the homogeneous system towards instability. The dependence of the drag coefficient on the spacing between two layers is determined by the form of particle-particle interaction.

Key words: Bose gas bilayers, dissipationless drag, collective modes.

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