Relation between squeezing of vacuum fluctuations, quantum entanglement and sub-shot noise in Raman scattering

TL;DR

This paper provides a comprehensive quantum analysis of Raman scattering, demonstrating how nonclassical properties like entanglement and squeezing emerge in different scattering regimes, with detailed phase and parameter dependencies.

Contribution

It offers the first detailed quantum description linking nonclassical features to specific Raman scattering conditions and parameters.

Findings

Observation of intermodal entanglement in Raman modes

Detection of vacuum squeezing and sub-shot noise effects

Dependence of nonclassicalities on phases, time, and coupling ratios

Abstract

A completely quantum description of Raman process is used to investigate the nonclassical properties of the modes in the stimulated, spontaneous and partially spontaneous Raman process. Both coherent scattering (where all the initial modes are coherent) and chaotic scattering (where initial phonon mode is chaotic and all the other modes are coherent) are studied. Nonclassical character of Raman process is observed by means of intermodal entanglement, single mode and intermodal squeezing of vacuum fluctuations, sub-shot noise and wave variances. Joint photon-phonon number and integrated-intensity distributions are then used to illustrate the observed nonclassicalities. Conditional and difference number distributions are also provided to illustrate the nonclassical character. The mutual relation between the obtained nonclassicalities and their variations dependent on phases, rescalled time and ratio of coupling constants are also reported.