Diode effect in microwave irradiated Josephson junctions with Yu-Shiba-Rusinov states

TL;DR

This paper demonstrates that microwave irradiation can induce a diode-like effect in Josephson junctions with Yu-Shiba-Rusinov states by breaking certain symmetries, resulting in highly tunable asymmetric critical currents.

Contribution

It introduces a method to achieve and control diode effects in Josephson junctions through microwave-induced symmetry breaking, independent of specific impurity states.

Findings

Microwave irradiation causes asymmetric critical currents in the junctions.

Asymmetry can be tuned via microwave amplitude and frequency.

Perfect diode behavior with vanishing critical current for one polarity is achievable.

Abstract

We investigate the critical current in microwave-irradiated Josephson junctions hosting Yu-Shiba-Rusinov states due to magnetic impurities. Under two conditions, namely, (i) the breaking of particle-hole symmetry in the normal sense by non-zero potential scattering, and (ii) the breaking of inversion symmetry either by unequal magnitudes of potential scattering and/or magnetic moments, microwave irradiation induces an additional phase-independent contribution to the current. This leads to asymmetric critical currents for opposite current polarities, an effect absent in the same junction without microwave irradiation. The asymmetry is highly tunable via the microwave amplitude and frequency, and we may even achieve perfect asymmetry where the critical current vanishes for one polarity, akin to a perfect diode. While Yu-Shiba-Rusinov states provide the ideal platform for a pronounced asymmetry, we find that as long as the two conditions (i) and (ii) above are met, our proposal does not necessarily depend upon them.