Drag Effect in Bose and Fermi Gases

Using Feynman diagrammatic technique, unified theory of superfluid drag (Andreev-Bashkin effect) was developed for two-component Bose systems, two-layer superconducting systems and coherent electron-polariton systems consisting in a superconductor coupled with an exciton-polariton Bose condensate. Analytical formulas describing this effect were derived and numerical calculations at realistic parameters were carried out. The superfluid drag density in a two-component Bose system is shown to be bounded from above by the density of noncondensed part of each Bose component. The counterpart of dissipative Coulomb drag in a two-layer Bose system, which coexists with the superfluid drag, was also studied. As shown, the Bose stimulation effects plays the key role in a formation of drag effects in Bose-condensed systems. Methods of experimental observation of the considered effects were discussed. In particular, the method to control superconducting current using a laser radiation in electron-polariton systems was proposed.