Time-dependent photon generation by superconducting thin-film rings irradiated by coherent microwave fields

TL;DR

This paper investigates how superconducting thin-film rings emit photons when irradiated by coherent microwave fields, revealing the dependence on ring size, fluxoid number, and the induced oscillations of Cooper pairs.

Contribution

It introduces a theoretical model for photon emission from superconducting rings under microwave irradiation, detailing the energy, angle distributions, and probabilities of photon generation.

Findings

Photon emission depends on ring size and fluxoid number.

Single-photon and two-photon emission probabilities are calculated.

Emission energy and angular distributions are characterized.

Abstract

When a thin-film ring with supercurrent is irradiated by coherent microwave field, the field induces coherent oscillations of all the Cooper pairs involved in the supercurrent. The oscillating charged condensate will emit photons with energies determined by the difference of quantized energy levels of the superconducting ring. This effect can be observed only in the rings, the thickness of which is less than both the field skin-depth and the London penetration depth. The probability of the microwave field-induced single-photon and two-photon emission is calculated. The energy - angle distributions of the emitted photons as a function of both the ring sizes and the fluxoid number trapped in the ring, are explored.