# Heralded multiphoton states with coherent spin interactions in waveguide QED

## TL;DR

This paper presents methods to generate highly entangled atomic states in waveguide QED systems, enabling the creation of high-fidelity multi-photon states through heralded protocols, with improved success probabilities in certain regimes.

## Contribution

The authors introduce two novel protocols for heralded atomic state preparation in waveguide QED, demonstrating enhanced performance over previous methods, especially in low Purcell factor regimes.

## Key findings

- High success probability for multi-atom systems with low Purcell factors
- Protocols enable mapping of atomic entanglement to photonic states
- Comparison shows improved efficiency over prior proposals

## Abstract

WaveguideQEDoffers the possibility of generating strong coherent atomic interactions either through appropriate atomic configurations in the dissipative regime or in the bandgap regime. In this work, we show how to harness these interactions in order to herald the generation of highly entangled atomic states, which afterwards can be mapped to generate single mode multi-photonic states with high fidelities.Weintroduce two protocols for the preparation of the atomic states, we discuss their performance and compare them to previous proposals. In particular, we show that one of them reaches high probability of success for systems with many atoms but low Purcell factors.