# Nonadiabatic Dynamics of Strongly Driven Diffusive Josephson Junctions

## TL;DR

This paper investigates how microwave irradiation affects the supercurrent in diffusive SNS Josephson junctions, revealing non-trivial modifications to the current-phase relation due to out-of-equilibrium quasiparticle distributions.

## Contribution

It demonstrates the phase-dependent impact of microwave fields on supercurrent and provides a theoretical framework using quasiclassical Green's functions for these effects.

## Key findings

- Microwave irradiation alters the harmonic content of the current-phase relation.
- Supercurrent reduction occurs near phase $\pi$ due to transitions across the Andreev gap.
- Theoretical results agree with experimental measurements of Josephson emission.

## Abstract

By measuring the Josephson emission of a diffusive Superconductor-Normal metal-Superconductor (SNS) junction at a finite temperature we reveal a non-trivial sensitivity of the supercurrent to microwave irradiation. We demonstrate that the harmonic content of the current-phase relation is modified due to the energy redistribution of quasiparticles in the normal wire induced by the electromagnetic field. The distortion originates from the phase-dependent out-of-equilibrium distribution function which is strongly affected by the ac-response of the spectral supercurrent. For phases close to $\pi$, transitions accross the Andreev gap are dynamically favored leading to a supercurrent reduction. This finding is supported by a comparison with the quasiclassical Green's function theory of superconductivity in diffusive SNS junctions under microwave irradiation.