A Josephson junction supercurrent diode

TL;DR

This paper reports the development of superconducting nonreciprocal Josephson junctions that exhibit supercurrent rectification, linking asymmetry in current-phase relations to magnetochiral anisotropy, with potential applications in dissipationless circuits.

Contribution

The authors demonstrate fully superconducting nonreciprocal devices using Josephson junctions on InAs quantum wells, measuring supercurrent rectification and deriving the supercurrent magnetochiral anisotropy coefficient for the first time.

Findings

Supercurrent rectification observed below transition temperature.

Asymmetry in current-phase relation linked to nonreciprocity.

Quantitative model explains experimental data.

Abstract

Transport is called nonreciprocal when not only the sign, but also the absolute value of the current, depends on the polarity of the applied voltage. It requires simultaneously broken inversion and time-reversal symmetries, e.g., by the interplay of spin-orbit coupling and magnetic field. So far, observation of nonreciprocity was always tied to resistivity, and dissipationless nonreciprocal circuit elements were elusive. Here, we engineer fully superconducting nonreciprocal devices based on highly-transparent Josephson junctions fabricated on InAs quantum wells. We demonstrate supercurrent rectification far below the transition temperature. By measuring Josephson inductance, we can link nonreciprocal supercurrent to the asymmetry of the current-phase relation, and directly derive the supercurrent magnetochiral anisotropy coefficient for the first time. A semi-quantitative model well explains the main features of our experimental data. Nonreciprocal Josephson junctions have the potential to become for superconducting circuits what $pn$-junctions are for traditional electronics, opening the way to novel nondissipative circuit elements.