Topologically non-trivial superfluid phases and Majorana fermions from Kohn-Luttinger effect

TL;DR

This paper proposes a simpler method to realize topological superfluid phases with Majorana fermions using the Kohn-Luttinger effect in spin-polarized fermions, bypassing complex experimental setups.

Contribution

It introduces a novel approach to create topological superfluids via the Kohn-Luttinger effect in two-species fermionic systems with density imbalance.

Findings

Topological superfluids can be achieved using the Kohn-Luttinger effect.

Majorana fermions can be identified with current experimental techniques.

The method simplifies the realization of topological superfluids.

Abstract

Spin-triplet p-wave superfluids of single-species (or spin-polarized) fermionic atoms is a topological superfluid. In 2D such a superfluid supports zero-energy topological Majorana fermion excitations in order parameter defects such as vortices and sample edges. In 3D these superfluids support topologically protected Dirac points in the bulk spectrum and flat surface Majorana arcs. Despite the promise, creating a spin-triplet p-wave single-species fermionic superfluid either from direct p-wave Feshbach resonance or indirectly from the recently proposed artificial spin-orbit and Zeeman couplings can be technologically challenging. Here we show that such topological superfluids can be far more simply created by using the Kohn-Luttinger effect applied to two species of spin-polarized fermions with a density imbalance. We discuss how the topological Majorana excitations of the resulting superfluids can be identified using recently-developed experimental techniques.