Superfluid density of a photo-induced superconducting state

TL;DR

This paper calculates the superfluid density of a photo-induced nonequilibrium superconducting state, demonstrating its stability and the presence of the Meissner effect even with repulsive interactions and interband pairing.

Contribution

It provides a theoretical calculation showing the superfluid density is positive in a nonequilibrium superconducting state induced by photo-excitation, indicating its stability.

Findings

Superfluid density is positive for repulsive interactions and interband pairing.

The positive superfluid density implies the stability of the photo-induced superconducting state.

The state exhibits the Meissner effect, confirming superconductivity.

Abstract

Nonequilibrium conditions offer novel routes to superconductivity that are not available at equilibrium. For example, by engineering nonequilibrium electronic populations, pairing may develop between electrons in different energy bands. A concrete proposal has been made to photo-induce superconductivity in a semiconductor, where pairing occurs between electrons in the conduction and valence bands, even for repulsive interactions. Here, we calculate the superfluid density for such a nonequilibrium paired state, and find it to be positive for repulsive interactions and interband pairing. The positivity of the superfluid density implies the stability of the photo-induced superconducting state as well as the existence of the Meissner effect.