Synthetic spin-orbit coupling in superconductor-semiconductor hybrid nanowires with micromagnet arrays

TL;DR

This paper demonstrates the creation of synthetic spin-orbit coupling in superconductor-semiconductor nanowires using micromagnet arrays with rotating magnetic fields, enabling control of spin states for quantum computing.

Contribution

It introduces a method to engineer synthetic spin-orbit coupling in nanowires via external magnetic fields, expanding possibilities for materials with low intrinsic spin-orbit interaction.

Findings

Achieved synthetic Rashba spin-orbit interaction coefficient of 0.022 eV nm.

Used transport spectroscopy to probe magnetic field profiles.

Reconfigurable micromagnet magnetization configurations demonstrated.

Abstract

Spin-orbit interaction accounts for the coupling of momentum and spin degrees of freedom of electrons and holes in semiconductor materials. In quantum information processing, it allows for electrical control of spin states and for the engineering of topologically protected Majorana zero modes. Although such functionalities were previously considered to be limited to semiconductor materials with strong intrinsic spin-orbit interactions only, recent theoretical work proposes using external rotating magnetic fields to engineer synthetic spin-orbit coupling. This would relax material constraints and open up new research directions for materials with low intrinsic spin-orbit interaction or augment existing spin-orbit interaction in materials in which this interaction is already strong. Here we demonstrate the feasibility of this approach and introduce rotating magnetic fields along an InAs/Al hybrid nanowire using permalloy micromagnet arrays which yields an estimated synthetic Rashba spin-orbit interaction coefficient of 0.022 eV nm. We use transport spectroscopy and the energy dependence of Andreev bound states in the nanowires as a probe of the magnetic field profiles of the micromagnets which are reconfigurably prepared in parallel or antiparallel magnetization configurations.