Nonequilibrium Josephson diode effect in periodically driven SNS junctions

TL;DR

This paper predicts a nonequilibrium Josephson diode effect in periodically driven SNS junctions, where symmetry breaking and driving induce asymmetric current-phase relations and anomalous currents, with the effect disappearing in the adiabatic limit.

Contribution

It introduces a novel nonequilibrium Josephson diode effect in driven SNS junctions, highlighting the role of symmetry breaking and dynamic driving in generating diode behavior.

Findings

Diode effect appears when symmetries are broken in driven SNS junctions.

Anomalous current arises without phase bias in certain configurations.

The diode effect vanishes in the adiabatic limit.

Abstract

In typical Josephson junctions, the Josephson current is an odd function of the superconducting phase difference. Recently, diode effect in Josephson junctions is observed in experiments wherein the maximum and the minimum values of the Josephson current in the current-phase relation do not have the same magnitude. We propose a superconductor-normal metal-superconductor (SNS) junction where Josephson diode effect manifests when the normal metal region is driven. Time reversal symmetry and inversion symmetry need to be broken in the SNS junction for the diode effect to show up. We calculate long time averaged current and show that the system exhibits diode effect for two configurations of the driven SNS junction - one in which inversion symmetry is broken in the undriven part of the Hamiltonian and the other wherein both the symmetries are broken by the driving potential. In the latter configuration, a nonzero current known as anomalous current appears at the junction in absence of phase bias. In the proposed setup, the diode effect vanishes in the adiabatic limit.