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

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 anti-Stokes scattered light, the latter may possess single-photon properties. We analyze the influence of 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 low value of the second-order autocorrelation function of the single-photon source is preserved even when the flow of uncorrelated photons exceeds the flow of correlated photons in scattered Raman light by an order of magnitude.