Phonon assisted tunneling in Josephson junctions

TL;DR

This paper derives an expression for subgap current in Josephson junctions considering electron-phonon interactions, revealing phonon-assisted tunneling effects that produce characteristic peaks in current-voltage behavior.

Contribution

It introduces a new theoretical model for phonon-assisted tunneling in Josephson junctions, linking electron-phonon interactions to observable features in current-voltage characteristics.

Findings

Peaks appear at Josephson frequencies related to Raman-active phonons.

The derived expression explains experimental subgap current features.

Phonon-assisted tunneling significantly influences Josephson junction behavior.

Abstract

The expression for additional subgap current in the presence of electron-phonon interaction is derived. We show that the phonon assisted tunneling leads to appearance of peaks on current-voltage characteristics at the Josephson frequencies corresponding to the Raman-active phonons. The relation of the obtained results to experimental observations are discussed.