# Photon blockade in weakly-driven cavity QED systems with many emitters

## TL;DR

This paper presents a scalable method to analyze photon blockade in multi-emitter cavity QED systems, revealing how emitter number and detuning affect photon blockade quality.

## Contribution

The authors develop an efficient scattering matrix approach that reduces computational complexity, enabling analysis of systems with around 50 emitters, and explore effects of detuning and inhomogeneous broadening.

## Key findings

- Photon blockade worsens with more emitters in resonant systems.
- Photon blockade improves with more emitters in detuned systems.
- Inhomogeneous broadening impacts photon blockade in complex ways.

## Abstract

We use the scattering matrix formalism to analyze photon blockade in coherently-driven CQED systems with a weak drive. By approximating the weak coherent drive by an input single- and two-photon Fock state, we reduce the computational complexity of the transmission and the two-photon correlation function from exponential to polynomial in the number of emitters. This enables us to easily analyze cavity-based systems containing $\sim$50 quantum emitters with modest computational resources. Using this approach we study the coherence statistics of polaritonic photon blockade while increasing the number of emitters for resonant and detuned multi-emitter CQED systems --- we find that increasing the number of emitters worsens photon blockade in resonant systems, and improves it in detuned systems. We also analyze the impact of inhomogeneous broadening in the emitter frequencies on both polaritonic and subradiant photon blockade through this system.