Majorana fermions in superconducting nanowires without spin-orbit coupling

TL;DR

This paper demonstrates that Majorana fermions can be realized in superconducting nanowires with a rotating magnetic field, eliminating the need for spin-orbit coupling, thus offering a new approach for Majorana systems.

Contribution

It introduces a method to generate Majorana fermions in nanowires through a rotating magnetic field, bypassing the need for spin-orbit coupling.

Findings

Majorana modes can exist with a rotating magnetic field.

Permanent magnets can induce topologically non-trivial phases.

The approach broadens the design options for Majorana systems.

Abstract

We show that confined Majorana fermions can exist in nanowires with proximity induced s-wave superconducting pairing if the direction of an external magnetic field rotates along the wire. The system is equivalent to nanowires with Rashba-type spin-orbit coupling, with strength proportional to the derivative of the field angle. For realistic parameters, we demonstrate that a set of permanent magnets can bring a nearby nanowire into the topologically non-trivial phase with localized Majorana modes at its ends. Without the requirement of spin-orbit coupling this opens up for a new route for demonstration and design of Majorana fermion systems.