Cavity Quantum Eliashberg Enhancement of Superconductivity

TL;DR

This paper theoretically demonstrates that coupling a 2D superconductor to a microwave cavity can enhance superconductivity through non-equilibrium quasiparticle redistribution, offering tunable control via cavity parameters.

Contribution

It introduces a quantum cavity approach to enhance superconductivity by manipulating electromagnetic fluctuations, extending the classical Eliashberg effect into the quantum regime.

Findings

Non-equilibrium quasiparticle redistribution enhances superconductivity.

Cavity environment tuning can optimize the superconducting state.

Predicted enhancement across various parameter regimes.

Abstract

Driving a conventional superconductor with an appropriately tuned classical electromagnetic field can lead to an enhancement of superconductivity via a redistribution of the quasiparticles into a more favorable non-equilibrium distribution -- a phenomenon known as the Eliashberg effect. Here we theoretically consider coupling a two-dimensional superconducting film to the quantized electromagnetic modes of a microwave resonator cavity. As in the classical Eliashberg case, we use a kinetic equation to study the effect of the fluctuating, dynamical electromagnetic field on the Bogoliubov quasiparticles. We find that when the photon and quasiparticle systems are out of thermal equilibrium, a redistribution of quasiparticles into a more favorable non-equilibrium steady-state occurs, thereby enhancing superconductivity in the sample. We predict that by tailoring the cavity environment (e.g. the photon occupation and spectral functions), enhancement can be observed in a variety of parameter regimes, offering a large degree of tunability.