Ideal pairing of the Stokes and anti-Stokes photons in the Raman process

TL;DR

This paper develops a quantum model of the Raman process to analyze nonclassical correlations between Stokes and anti-Stokes photons, revealing conditions for photon pair generation even with thermal phonons.

Contribution

It introduces a comprehensive quantum model for the Raman process with independent Stokes and anti-Stokes interactions, analyzing various quantum correlation measures and conditions for photon pair production.

Findings

Conditions for photon pair generation with thermal phonons are identified.

Multiple quantum correlation metrics are analyzed to characterize the Stokes and anti-Stokes fields.

The model elucidates how pump amplitude and vibrational mode properties influence correlations.

Abstract

A quantum model of the Raman process with the independent Stokes and anti-Stokes nonlinear interactions is developed to study nonclassical correlations between the photons in the Stokes and anti-Stokes fields. The role of the laser pump amplitude, the ratio of the Stokes and anti-Stokes coupling constants and the population and losses of the vibrational mode in forming the correlations is elucidated. The $ g^{(2)} $ intensity cross-correlation function, noise-reduction-factor, two-mode principal squeezing variance, logarithmic negativity, non-classicality depth, steering parameter and the Bell parameter are analyzed side-by-side to shed light to the correlations between the Stokes and anti-Stokes fields. Conditions for having the Stokes and anti-Stokes fields composed of only photon pairs, similarly as it occurs in twin beams in parametric down-conversion, are revealed. They allow for nonzero mean thermal phonon numbers.