Spin-orbit splitting of Andreev states revealed by microwave spectroscopy

L Tosi (1) , C. Metzger (1) , M F Goffman (1) , C. Urbina (1) , H. Pothier (1) , Sunghun Park (2) , A Levy Yeyati (2) , J. Nygård (3) , P. Krogstrup (3)

1 QUANTRONICS - Quantronics Group
2 UAM - Universidad Autónoma de Madrid
3 Center for Quantum Devices and Station Q Copenhagen

We have performed 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 $\pi.$ We interpret these 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.

Domaines: Systèmes mésoscopiques et effet Hall quantique [cond-mat.mes-hall]; Supraconductivité [cond-mat.supr-con]

L Tosi, C. Metzger, M F Goffman, C. Urbina, H. Pothier, et al.. Spin-orbit splitting of Andreev states revealed by microwave spectroscopy. Physical Review X, 2019, 9, pp.011010. ⟨10.1103/PhysRevX.9.011010⟩. ⟨hal-01888992v2⟩