Engineering and manipulating topological qubits in 1D quantum wires

TL;DR

This paper explores how magnetic field orientation influences the Josephson effect in topological and normal phases of 1D heterostructures, revealing a new magnetic coupling that enables control of Majorana qubits and spin currents.

Contribution

It introduces a novel magnetic contribution to the Majorana Josephson coupling, allowing magnetic field orientation to tune the Josephson current and manipulate topological qubits in 1D quantum wires.

Findings

Magnetic field orientation affects Josephson current in topological wires.

A new magnetic coupling enables control of Majorana bound states.

Spin currents can be generated by superconducting phase differences.

Abstract

We investigate the Josephson effect in TNT and NTN junctions, consisting of topological (T) and normal (N) phases of semiconductor-superconductor 1D heterostructures in the presence of a Zeeman field. A key feature of our setup is that, in addition to the variation of the phase of the superconducting order parameter, we allow the orientation of the magnetic field to change along the junction. We find a novel magnetic contribution to the Majorana Josephson coupling that permits the Josephson current to be tuned by changing the orientation of the magnetic field along the junction. We also predict that a spin current can be generated by a finite superconducting phase difference, rendering these materials potential candidates for spintronic applications. Finally, this new type of coupling not only constitutes a unique fingerprint for the existence of Majorana bound states but also provides an alternative pathway for manipulating and braiding topological qubits in networks of wires.