Correlated spin currents generated by resonant crossed Andreev reflections in topological superconductors

TL;DR

This paper proposes a new type of topological superconductor that generates correlated, spin-polarized currents via Majorana-induced resonant crossed Andreev reflections, with potential applications in quantum computing.

Contribution

It introduces a novel topological superconductor design based on AIII class topological insulators and quantum anomalous Hall insulators, enabling efficient Cooper pair splitting and correlated spin currents.

Findings

Topological superconductor supports two Majorana fermion end states.

Efficient splitting of Cooper pairs into spin-polarized currents.

Realization possible with quantum anomalous Hall insulators and superconductors.

Abstract

Topological superconductors, which support Majorana fermion excitations, have been the subject of intense studies due to their novel transport properties and their potential applications in fault-tolerant quantum computations. Here we propose a new type of topological superconductors which can be used as a novel source of correlated spin currents. We show that inducing superconductivity on a AIII class topological insulator wire, which respects a chiral symmetry and supports protected fermionic end states, will result in a topological superconductor. This topological superconductor supports two topological phases with one or two Majorana fermion end states respectively. In the phase with two Majorana fermions, the superconductor can split Cooper pairs efficiently into electrons in two spatially separated leads due to Majorana induced resonant crossed Andreev reflections. The resulting currents in the leads are correlated and spin-polarized. Importantly, the proposed topological superconductors can be realized using quantum anomalous Hall insulators in proximity to superconductors.