Highly bright photon-pair generation in Doppler-broadened ladder-type atomic system

TL;DR

This paper demonstrates a highly bright photon-pair source using Doppler-broadened atomic ensembles, achieving high coincidence rates and strong quantum correlations, advancing quantum communication technologies.

Contribution

It introduces a novel scheme leveraging Doppler broadening to significantly enhance photon-pair generation in atomic systems.

Findings

Photon-pair generation rate of tens of thousands cps/mW.

Violation of Cauchy-Schwarz inequality by a factor of 2370.

Effective use of Doppler broadening for quantum light sources.

Abstract

We report a bright photon-pair source with a coincidence counting rate per input power (cps/mW) of tens of thousands, obtained via spontaneous four-wave mixing from a Doppler-broadened atomic ensemble of the 5S1/2-5P3/2-5D5/2 transition of 87Rb. The photon-pair generation rate is enhanced by the two-photon coherence contributions from almost all the atomic velocity groups in the Doppler-broadened ladder-type atomic system. We obtained the violation of the Cauchy-Schwarz inequality by a factor of 2370(150). We believe that our scheme for highly bright paired photons is important as a useful quantum light source for quantum entanglement swapping between completely autonomous sources.