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
Department of Physics, Bilkent University, Ankara 06800, Turkey
Received December 3, 2019, published online March 24, 2020
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.