Microwave-Tunable Diode Effect in Asymmetric SQUIDs with Topological Josephson Junctions

TL;DR

This paper investigates the microwave-tunable Josephson diode effect in asymmetric SQUIDs combining topological and trivial Josephson junctions, revealing how magnetic fields and AC power influence diode polarity and response.

Contribution

It introduces the study of the Josephson diode effect in topological SQUIDs with 4π-periodic JJs and demonstrates tunability of diode polarity via magnetic field and AC power.

Findings

Diode polarity can be switched by tuning magnetic field and trivial junction parameters.

The AC response of topological SQUIDs shows distinct diode behavior compared to trivial SQUIDs.

The fractional Josephson effect influences the diode effect in topological SQUIDs.

Abstract

In superconducting systems in which inversion and time-reversal symmetry are simultaneously broken the critical current for positive and negative current bias can be different. For superconducting systems formed by Josephson junctions (JJs) this effect is termed Josephson diode effect. In this work, we study the Josephson diode effect for a superconducting quantum interference device (SQUID) formed by a topological JJ with a 4$\pi$-periodic current-phase relationship and a topologically trivial JJ. We show how the fractional Josephson effect manifests in the Josephson diode effect with the application of a magnetic field and how tuning properties of the trivial SQUID arm can lead to diode polarity switching. We then investigate the AC response and show that the polarity of the diode effect can be tuned by varying the AC power and discuss differences between the AC diode effect of asymmetric SQUIDs with no topological JJ and SQUIDs in which one JJ is topological.