Critical velocities in two-component superfluid Bose gases
Abstract
On the ground of the Landau criterion we study the behavior of critical velocities in a superfluid two-component Bose gas. It is found that under motion of the components with different velocities the velocity of each component should not be lower than a minimum phase velocity of elementary excitations (s). The Landau criterion yields a relation between the critical velocities of the components (vc1, vc2). The velocity of one or even both components may exceed s. The maximum value of the critical velocity of a given component can be reached when the other component does not move. The approach is generalized for a two-component condensate confined in a cylindrical harmonic potential. PACS numbers: 03.75.Kk,03.75.Mn
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