Majorana spintronics

TL;DR

This paper introduces a flux-free, electrically controllable method to detect, manipulate, and braid Majorana fermions in semiconductor nanowires, leveraging a tunable spin-phase to enable topological quantum operations.

Contribution

It presents a novel approach using spin properties and electric control to manipulate Majorana zero modes without magnetic flux, advancing topological quantum computing techniques.

Findings

Identification of a spin-dependent superconducting phase (spin-phase)

Demonstration of electric control over the spin-phase via spin-orbit coupling

Proposal of a flux-free, all-electrical Majorana manipulation and detection scheme

Abstract

We propose a systematic magnetic-flux-free approach to detect, manipulate and braid Majorana fermions in a semiconductor nanowire-based topological Josephson junction by utilizing the Majorana spin degree of freedom. We find an intrinsic $\pi$-phase difference between spin-triplet pairings enforced by the Majorana zeros modes (MZMs) at the two ends of a one-dimensional spinful topological superconductor. This $\pi$-phase is identified to be a spin-dependent superconducting phase, referred to as the spin-phase, which we show to be tunable by controlling spin-orbit coupling strength via electric gates. This electric controllable spin-phase not only affects the coupling energy between MZMs but also leads to a fractional Josephson effect in the absence of any applied magnetic flux, which enables the efficient topological qubit readout. We thus propose an all-electrically controlled superconductor-semiconductor hybrid circuit to manipulate MZMs and to detect their non-Abelian braiding statistics properties. Our work on spin properties of topological Josephson effects potentially opens up a new thrust for spintronic applications with Majorana-based semiconductor quantum circuits.