The gate-tuneable Josephson diode

Superconducting diodes are a recently-discovered quantum analog of classical diodes. The superconducting diode effect relies on the breaking of both time-reversal and inversion symmetry. As a result, the the critical current of a superconductor can become dependent on the direction of the applied current. The combination of these ingredients naturally occurs in proximitized semiconductors under a magnetic field. There, it is also predicted to give rise to exotic physics such as topological superconductivity. In this work, we use InSb nanowires proximitized by Al to investigate the superconducting diode effect. Through shadow-wall lithography, we create short Josephson junctions with gate control of both the junction as well as the proximitized leads. We identify two distinct physical mechanisms both leading to a superconducting diode effect. In the proximitized leads, a magnetic field perpendicular to the nanowire axis can be used to generate finite momentum cooper-pairing, which results in a maximum diode effect whenever the applied field is parallel to the spin-orbit direction. On the other hand, interference of multiple modes in the junction can also result in a finite diode effect, which occurs even when the field is applied parallel to the current flow in the nanowire. Both effects exhibit a strong dependence on the electrostatic gate voltages. This makes the semiconductor-superconductor hybrid Josephson diode the ideal element for innovative superconducting computation devices.