Microwave control of the superconducting proximity effect and minigap in magnetic and normal metals

TL;DR

This paper theoretically shows that microwave irradiation can actively control the spectral properties, minigap, and triplet proximity effect in superconducting proximity structures, enabling dynamic manipulation of quantum coherence.

Contribution

It introduces a theoretical framework demonstrating how light can modulate spectral features and proximity effects in normal and magnetic metals within superconducting structures.

Findings

Microwave irradiation can alter the minigap size in proximity structures.

Light can induce a zero-energy quasiparticle peak at resonance.

Spectral properties are controllable via microwave frequency and intensity.

Abstract

We demonstrate theoretically that shining light on superconducting proximity structures controls the minigap and triplet proximity effect in normal and magnetic metals, respectively. Considering both a bilayer and Josephson junction geometry, we show that microwave irradiation with frequency $\omega$ qualitatively alters the spectral properties of the system, controlling the minigap size $E_\text{mg}$ and even replacing the minigap with a strong peak of quasiparticle accumulation at zero energy when $\omega=E_\text{mg}$. The interaction between light and Cooper pairs may thus open a route to active control of quantum coherent phenomena in superconducting proximity structures.