Microwave Dressed States and Vacuum Fluctuations in a Superconducting Condensate

TL;DR

This paper explores how microwave fields and vacuum fluctuations influence superconducting states, revealing enhanced energy gaps and back-action effects that extend existing theories of superconductivity.

Contribution

It introduces a quantum model of microwave-enhanced superconductivity that accounts for vacuum fluctuations and back-action effects, expanding beyond Eliashberg's non-equilibrium theory.

Findings

Microwave dressed states emerge within the superconducting condensate.

Energy separation exceeds BCS predictions and depends on photon number.

Superconducting condensate suppresses electromagnetic vacuum fluctuations.

Abstract

Microwave dressed states are found to emerge within the superconducting condensate when coupled to a quantized electromagnetic field due to photon-Cooper pair entanglement. The renormalized energy separation between these states exceeds the prediction of BCS theory, with the enhancement depending on the number of photons and also arising from electromagnetic vacuum fluctuations. Our work introduces an equilibrium quantum model of microwave-enhanced superconductivity, expanding the theoretical description beyond Eliashberg's non-equilibrium theory. We further demonstrate that the superconducting condensate exerts a back-action on the electromagnetic field, suppressing electric field fluctuations, including those from the vacuum state. This result is consistent with Glauber and Lewenstein's field quantization in dielectric media.