# Photon Correlations from the Mollow Triplet

## TL;DR

This paper provides a comprehensive analysis of photon correlations in the Mollow triplet, revealing complex multi-photon physics and proposing methods to optimize it as a tunable, highly correlated photon source.

## Contribution

It offers the first full characterization of photon correlations at all orders without frequency restrictions, highlighting the role of virtual photons in multi-photon emission.

## Key findings

- Photon correlations are stronger between the peaks due to virtual photon transitions.
- Emissions occur in photon bundles rather than successively, indicating complex multi-photon physics.
- Frequency filtering can turn the Mollow triplet into a versatile photon source.

## Abstract

Photon correlations between the photoluminescence peaks of the Mollow triplet have been known for a long time, and recently hailed as a resource for heralded single-photon sources. Here, we provide the full picture of photon-correlations at all orders (we deal explicitly with up to four photons) and with no restriction to the peculiar frequency windows enclosing the peaks. We show that a rich multi-photon physics lies between the peaks, due to transition involving virtual photons, and thereby much more strongly correlated than those transiting through the dressed states. Specifically, we show that such emissions occur in bundles of photons rather than as successive, albeit correlated, photons. We provide the recipe to frequency-filter the emission of the Mollow triplet to turn it into a versatile and tunable photon source, allowing in principle all scenarios of photon emission, with advantages already at the one-photon level, i.e., providing more strongly correlated heralded single-photon sources than those already known.