Rostock 2019 – scientific programme

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Q: Fachverband Quantenoptik und Photonik

Q 28: Quantum Gases (Bosons) III

Q 28.6: Talk

Wednesday, March 13, 2019, 12:00–12:15, S HS 037 Informatik

Coupled superfluidity in binary Bose mixtures in two dimensions — •Volker Karle — Ruprecht-Karls-Universität Heidelberg

We consider a two-component Bose gas in two dimensions at low temperature with short-range repulsive interaction. In the coexistence phase where both components are superfluid, inter-species interactions induce a nondissipative drag between the two superfluid flows (Andreev-Bashkin effect). We show that this behavior leads to a modification of the usual Berezinskii-Kosterlitz-Thouless(BKT) transition in two dimensions. We extend the renormalization of the superfluid densities at finite temperature using the renormalization group approach and find that the vortices of one component have a large influence on the superfluid properties of the other, mediated by the nondissipative drag. The renormalization group flow implies that the topological vortex unbinding transition in one component can lead to the collapse of superfluidity also in the other component, and thereby couple their critical temperatures to a unique value.