Electric control of polarity in a spin-orbit Josephson diode

The effect of spin-orbit coupling in a Josephson diode has not been elucidated due to its interplay with the complexity of Josephson devices. Here, we systematically control local electric fields in epitaxial Al-InAs Josephson junctions under in-plane magnetic fields and observe a polarity reversal of the Josephson diode. We interpret this polarity reversal as an effect of field-tunable spin-orbit coupling on nonreciprocal Josephson currents. A theoretical model, accounting for Rashba and Dresselhaus spin-orbit couplings in a planar Josephson junction containing many transverse subbands, aligns with the observed polarity reversal and its dependence on magnetic field. Our finding addresses spin-orbit control in a Josephson diode, enabling manipulation of Josephson harmonics.