Topological superfluid in a Fermi-Bose mixture with a high critical temperature

TL;DR

This paper proposes a method to realize a topological superfluid with a high critical temperature in a 2D Fermi gas immersed in a 3D BEC, using tunable interactions and BKT theory to optimize superfluid properties.

Contribution

It demonstrates that a 2D spin-polarized Fermi gas in a 3D BEC can host a topological superfluid with a high critical temperature, with tunable interactions and realistic experimental conditions.

Findings

Induced interactions mediate pairing in the Fermi gas.

Critical temperature can approach the BKT maximum.

Weak Fermi-Bose interactions reduce three-body losses.

Abstract

We show that a two-dimensional (2D) spin-polarised Fermi gas immersed in a 3D Bose-Einstein condensate (BEC) constitutes a very promising system to realise a $p_x+ip_y$ superfluid. The fermions attract each other via an induced interaction mediated by the bosons, and the resulting pairing is analysed with retardation effects fully taken into account. This is further combined with Berezinskii-Kosterlitz-Thouless (BKT) theory to obtain reliable results for the superfluid critical temperature. We show that both the strength and the range of the induced interaction can be tuned experimentally, which can be used to make the critical temperature approach the maximum value allowed by general BKT theory. Moreover, this is achieved while keeping the Fermi-Bose interaction weak so that three-body losses are small. Our results show that realising a topological superfluid with atomic Fermi-Bose mixtures is within experimental reach.