Heralded single-photon source based on ensemble of Raman active molecules

TL;DR

This paper explores using Raman scattering in molecules to develop heralded single-photon sources for quantum communication, demonstrating high purity even with significant background noise.

Contribution

It proposes a novel method of creating heralded single-photon sources using Raman scattering and analyzes factors affecting their purity and efficiency.

Findings

High purity of single-photon source maintained despite uncorrelated photon flow

Effective postselection of anti-Stokes photons using Stokes scattered light

Analysis of factors like time delay and background radiation impact

Abstract

Light with high mutual correlations at different frequencies can be used to create heralded single-photon sources, which may serve as the basic elements of existing quantum cryptography and quantum teleportation schemes. One of the important examples in natural systems of light with high mutual correlations is the light produced by spontaneous Raman scattering on an ensemble of molecules. In this paper, we investigate the possibility of using Raman light to create a heralded single-photon source. We show that when using Stokes scattered light for postselection of an anti-Stokes scattered light, the latter may posses the single-photon properties. We analyze the influence of the various negative factors on the characteristics of such a heralded single-photon source, which include a time delay between Stokes and anti-Stokes photons, the finiteness of the correlation radius of an external source, and background radiation. We show that the high purity of the single-photon source is preserved even when the flow of uncorrelated photons exceeds the flow of correlated photons in the scattered Raman light by an order of magnitude.