Numerical investigation of the quantum fluctuations of optical fields transmitted through an atomic medium

TL;DR

This paper numerically investigates quantum fluctuations and squeezing phenomena in optical fields transmitted through an atomic medium, considering detailed atomic structures and polarization effects.

Contribution

It introduces a comprehensive numerical model that includes Zeeman sublevels, polarization components, and atomic quantum fluctuations to analyze noise spectra and entanglement.

Findings

Generation of squeezing in the driving field polarization

Vacuum squeezing in the orthogonal polarization

Predicted entanglement between orthogonal modes

Abstract

We have numerically solved the Heisenberg-Langevin equations describing the propagation of quantized fields through an optically thick sample of atoms. Two orthogonal polarization components are considered for the field and the complete Zeeman sublevel structure of the atomic transition is taken into account. Quantum fluctuations of atomic operators are included through appropriate Langevin forces. We have considered an incident field in a linearly polarized coherent state (driving field) and vacuum in the perpendicular polarization and calculated the noise spectra of the amplitude and phase quadratures of the output field for two orthogonal polarizations. We analyze different configurations depending on the total angular momentum of the ground and excited atomic states. We examine the generation of squeezing for the driving field polarization component and vacuum squeezing of the orthogonal polarization. Entanglement of orthogonally polarized modes is predicted. Noise spectral features specific of (Zeeman) multi-level configurations are identified.