Correlation functions in resonance fluorescence with spectral resolution: Signal-processing approach

TL;DR

This paper develops an analytical framework for spectral correlation functions in resonance fluorescence, using signal processing and diagrammatic methods, with applications to interferometric measurements and spectral cascade analysis.

Contribution

It introduces a general analytical formula for spectral correlation functions passing through Fabry-Perot interferometers, advancing the theoretical understanding of spectral correlations in resonance fluorescence.

Findings

Derived an analytical formula for arbitrary-order spectral correlations.

Analyzed second-order temporal intensity correlations with interferometers.

Explored spectral correlations via two-photon cascades in dressed states.

Abstract

In the framework of the signal processing approach to single-atom resonance fluorescence with spectral resolution, we diagrammatically derive an analytical formula for arbitrary-order spectral correlation functions of the scattered fields that pass through Fabry-Perot interferometers. Our general expression is then applied to study correlation signals in the limit of well separated spectral lines of the resonance fluorescence spectrum. In particular, we study the normalized second-order temporal intensity correlation functions in the case of the interferometers tuned to the components of the spectrum and obtain interferential corrections to the approximate results derived in the secular limit. In addition, we explore purely spectral correlations and show that they can fully be understood in terms of the two-photon cascades down the dressed state ladder.