Andreev-Bashkin effect in superfluid cold gases mixtures

Year: 2017

Authors: Nespolo J., Astrakharchik GE., Recati A.

Autors Affiliation: Ludwig Maximilians Univ Munchen, Arnold Sommerfeld Ctr Theoret Phys, Dept Phys, Theresienstr 37, D-80333 Munich, Germany; Univ Politecn Cataluna, Dept Fis, E-08034 Barcelona, Spain; Univ Trento, INO CNR BEC Ctr, Via Sommarive 14, I-38123 Povo, Italy; Univ Trento, Dipartimento Fis, Via Sommarive 14, I-38123 Povo, Italy.

Abstract: We study a mixture of two superfluids with density-density and current-current (Andreev-Bashkin) interspecies interactions. The Andreev-Bashkin coupling gives rise to a dissipationless drag (or entrainment) between the two superfluids. Within the quantum hydrodynamics approximation, we study the relations between speeds of sound, susceptibilities and static structure factors, in a generic model in which the density and spin dynamics decouple. Due to translational invariance, the density channel does not feel the drag. The spin channel, instead, does not satisfy the usual Bijl-Feynman relation, since the f-sum rule is not exhausted by the spin phonons. The very same effect on one dimensional Bose mixtures and their Luttinger liquid description is analysed within perturbation theory. Using diffusion quantum Monte Carlo simulations of a system of dipolar gases in a double layer configuration, we confirm the general results. Given the recent advances in measuring the counterflow instability, we also study the effect of the entrainment on the dynamical stability of a superfluid mixture with non-zero relative velocity.

Journal/Review: NEW JOURNAL OF PHYSICS

Volume: 19      Pages from: 125005-1  to: 125005-14

More Information: We acknowledge useful discussions with Giovanni Barontini, Stefano Giorgini, Francesco Minardi, Lode Pollet and Sandro Stringari. GEA acknowledges partial financial support from the MICINN (Spain) Grant No. FIS2014-56257-C2-1-P. The Barcelona Supercomputing Center (The Spanish National Supercomputing Center-Centro Nacional de Supercomputacion) is acknowledged for the computational facilities provided. JN acknowledges support from the European Research Council through FP7/ERC Starting Grant No. 306897. The authors gratefully acknowledge the Gauss Centre for Supercomputing eV (gauss-centre.eu) for funding this project by providing computing time on the GCS Supercomputer SuperMUC at Leibniz Supercomputing Centre (LRZ, lrz.de).
KeyWords: multicomponent superfluids; Andreev-Bashkin effect; dipolar gases; diffusion quantum Monte Carlo; sum rules
DOI: 10.1088/1367-2630/aa93a0

Citations: 42
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