Nonlinear Resonance of Superconductor/Normal Metal Structures to Microwaves

TL;DR

This paper investigates how microwave radiation influences the differential conductance in superconductor/normal metal heterostructures using quasiclassical Green's functions, revealing nonlinear resonance effects under different limiting conditions.

Contribution

It provides a theoretical analysis of microwave-induced nonlinear resonance in superconductor/normal metal structures considering two distinct limiting regimes.

Findings

Differential conductance varies nonlinearly with microwave radiation.

Resonance effects depend on the proximity effect strength and microwave frequency.

Theoretical predictions align with potential experimental observations.

Abstract

We study the variation of the differential conductance $G=dj/dV$ of a normal metal wire in a Superconductor/Normal metal heterostructure with a cross geometry under external microwave radiation applied to the superconducting parts. Our theoretical treatment is based on the quasiclassical Green's functions technique in the diffusive limit. Two limiting cases are considered: first, the limit of a weak proximity effect and low microwave frequency, second, the limit of a short dimension (short normal wire) and small irradiation amplitude.