# Photon correlations in both time and frequency

## TL;DR

This paper develops a comprehensive theory of photon correlations in both time and frequency, providing exact calculations and novel insights into quantum optical systems, with practical implications for measurements and analysis.

## Contribution

The paper introduces an exact theoretical framework for frequency- and time-resolved photon correlations, extending previous approximations and including photon bundle correlations.

## Key findings

- Exact results for photon correlations in complex systems
- Comparison showing improvements over previous approximations
- Highlighting the importance of joint time-frequency measurements

## Abstract

We summarise the main results that follow from our theory of frequency- and time-resolved photon correlations, which provides exact computations in nontrivial systems. We illustrate the theory with original results as interesting cases can be picked up from the endless configurations that abound in any quantum optical system. In particular, we compare our exact results with previous approximations, upgrade correlations to the case of photon bundles as otherwise no clear physical picture emerge, highlight the interest of measuring away from the peaks in rich landscapes of correlations and emphasize the joint time and frequency aspect of our theory.