Odd-frequency Superconductivity in Driven Systems

TL;DR

This paper demonstrates that Berezinskii's classification of Cooper pair symmetries applies to driven, non-translation-invariant systems, revealing how external driving induces odd-frequency pairing and modifies spectral properties.

Contribution

It extends the classification of superconducting pair symmetries to driven systems and analyzes how external drives generate odd-frequency components in Green's functions.

Findings

External drive induces odd-frequency terms in Green's functions

Driving modifies the density of states and spectral function features

Berezinskii's classification remains valid in driven, non-uniform systems

Abstract

We show that Berezinskii's classification of the symmetries of Cooper pair amplitudes holds for driven systems even in the absence of translation invariance. We then consider a model Hamiltonian for a superconductor coupled to an external driving potential and, treating the driving potential as a perturbation, we investigate the corrections to the anomalous Green's function, density of states, and spectral function. We find that in the presence of an external drive the anomalous Green's function develops terms that are odd in frequency and that the same mechanism responsible for these odd-frequency terms generates additional features in the density of states and spectral function.