Universal Josephson diode effect

We propose a universal mechanism for the Josephson diode effect in short Josephson junctions. The proposed mechanism is due to finite Cooper pair momentum and is a manifestation of simultaneous breaking of inversion and time-reversal symmetries. The diode efficiency is up to 40%, which corresponds to an asymmetry between the critical currents in opposite directions Ic+/Ic- approximate to 230%. We show that this arises from both the Doppler shift of the Andreev bound state energies and the phase-independent asymmetric current from the continuum. Last, we propose a simple scheme for achieving finite-momentum pairing, which does not rely on spin-orbit coupling and thus greatly expands existing platforms for the observation of supercurrent diode effects.

Automated summary

We propose a universal mechanism for the Josephson diode effect in short Josephson junctions, which arises from finite Cooper pair momentum and simultaneous breaking of inversion and time-reversal symmetries. The diode efficiency is up to 40% with an asymmetry between the critical currents in opposite directions of approximately 230%. The mechanism is explained by the Doppler shift of the Andreev bound state energies and the phase-independent asymmetric current from the continuum. We also introduce a simple scheme for achieving finite-momentum pairing without relying on spin-orbit coupling, expanding the platforms for observing supercurrent diode effects.