Quantum atom-light interfaces in the gaussian description for spin-1 systems

TL;DR

This paper extends the Gaussian covariance-matrix framework to accurately model spin-1 atom-light interfaces, including noise effects, validated by experiments with polarized rubidium atoms, enabling better understanding of quantum measurements in complex atomic systems.

Contribution

It introduces a comprehensive Gaussian model for spin-1 systems that incorporates alignment degrees of freedom and common experimental noise sources, enhancing the modeling of atom-light quantum interfaces.

Findings

The extended model accurately reproduces experimental FID measurements.

Inclusion of noise terms improves the model's realism and applicability.

The approach can be generalized to larger spin systems and complex setups.

Abstract

We extend the covariance-matrix description of atom--light quantum interfaces, originally developed for real and effective spin-1/2 atoms, to include "spin alignment" degrees of freedom. This allows accurate modeling of optically-probed spin-1 ensembles in arbitrary magnetic fields. We also include technical noise terms that are very common in experimental situations. These include magnetic field noise, variable atom number and the effect of magnetic field inhomogeneities. We demonstrate the validity of our extended model by comparing numerical simulations to a free--induction decay (FID) measurement of polarized $^{87}$Rb atoms in the $f = 1$ ground state. We qualitatively and quantitatively reproduce experimental results with all free parameters of the simulations fixed. The model can be easily extended to larger spin systems, and adapted to more complicated experimental situations.