# Superradiance as a witness to multipartite entanglement

**Authors:** Frederik Lohof, Daniel Schumayer, David A. W. Hutchinson, Christopher Gies  
**arXiv:** [2303.12515](https://arxiv.org/abs/2303.12515)  
**Date:** 2023-03-22  
**Summary page:** https://www.summarizepaper.com/en/paper/2303.12515v1/

## Key points

- Generation and detection of entanglement are crucial in quantum information technologies
- Various techniques, including the use of entanglement witnesses, have been developed to reveal entanglement based on partial information about the quantum state
- Superradiance is a phenomenon where synchronized photon emission occurs from quantum emitters due to correlations among particles
- Physicist Dicke linked superradiance to multipartite entangled states
- Recent study by Lohof, Schumayer, Hutchinson, and Gies explores the connection between superradiance and multipartite entanglement quantitatively
- Signatures of superradiance in semiconductor nanolasers may serve as a witness for detecting entanglement within emitter ensembles' underlying state
- Study reveals that sub- and superradiance are not directly tied to Dicke-states but result from a combination of angular momentum eigenstates with both contributions
- Researchers establish a relationship between emitter correlations affecting emission rates and an effective method for detecting Dicke-state entanglement
- Utilizing Fock-state quantum light could generate transiently entangled Dicke states detectable through accessible entanglement witnesses
- Superradiant light emission can serve as a signature of multipartite entanglement within emitter ensembles when coupled with specific experimental setups

## Summary

In the field of quantum information technologies, the generation and detection of entanglement play a crucial role. Various techniques have been developed to reveal entanglement based on partial information about the underlying quantum state, including the use of entanglement witnesses. Superradiance is a phenomenon where highly synchronized photon emission occurs from a group of quantum emitters due to correlations among the individual particles. This concept has been linked by physicist Dicke to the presence of multipartite entangled states. A recent study by Frederik Lohof, Daniel Schumayer, David A. W. Hutchinson, and Christopher Gies delves into this connection between superradiance and multipartite entanglement in a quantitative manner. The researchers investigate whether signatures of superradiance observed in semiconductor nanolasers can serve as a witness for detecting entanglement within the emitters' underlying state. Contrary to previous expectations linking sub- and superradiance to modifications in spontaneous emission time in correlated emitter ensembles, the study reveals that these phenomena are not directly tied to Dicke-states. Instead, they result from a combination of angular momentum eigenstates with both sub- and superradiant contributions that are predominantly not Dicke-states. By combining insights from semiconductor optics and quantum information theory, the researchers establish a close relationship between emitter correlations affecting spontaneous emission rates and an effective method for detecting Dicke-state entanglement. They conclude that while the emission pulse characteristic of Dicke superradiance is not necessarily indicative of entanglement, utilizing Fock-state quantum light to excite cavity QED systems could generate transiently entangled Dicke states detectable through accessible entanglement witnesses. The proposed approach suggests that superradiant light emission can serve as a signature of multipartite entanglement within emitter ensembles when coupled with specific experimental setups. This research opens up new avenues for understanding the complex interplay between superradiance, multipartite entanglement, and quantum technologies at large.