Spin-Orbit Splitting of Andreev States Revealed by Microwave Spectroscopy

Article: published in Physical Review X by Sunghun Park,  Alfredo Levy Yeyati, IFIMAC researcher and member of the Department of Theoretical Condensed Matter Physics.

We perform microwave spectroscopy of Andreev states in superconducting weak links tailored in an InAs-Al (core-full shell) epitaxially grown nanowire. The spectra present distinctive features with bundles of four lines crossing when the superconducting phase difference across the weak link is 0 or π. We interpret these features as arising from zero-field spin-split Andreev states. A simple analytical model, which takes into account the Rashba spin-orbit interaction in a nanowire containing several transverse subbands, explains these features and their evolution with magnetic field. Our results show that the spin degree of freedom is addressable in Josephson junctions and constitute a first step towards its manipulation. [Full article]

Synopsis: Putting a Spin on the Josephson Effect