# Superradiant parametric conversion of spin waves

## TL;DR

This paper introduces a scheme to generate spatially-structured superradiant states using atomic spin waves, enabling the conversion of long-lived spin excitations into photon pairs for advanced quantum optics applications.

## Contribution

It presents a novel method to prepare superradiant states in atomic ensembles via spin-wave light storage, facilitating nonlinear optics with spin waves.

## Key findings

- Demonstration of spatially-structured superradiant states
- Conversion of atomic spin waves into photon pairs
- Potential for nonlinear spin wave optics

## Abstract

Atomic-ensemble spin waves carrying single-photon Fock states exhibit nonclassical many-body correlations in-between atoms. The same correlations are inherently associated with single-photon superradiance, forming the basis of a plethora of quantum light-matter interfaces. We devise a scheme allowing the preparation of spatially-structured superradiant states in the atomic two-photon cascade using spin-wave light storage. We thus show that long-lived atomic ground-state spin waves can be converted to photon pairs opening the way towards nonlinear optics of spin waves via multi-wave mixing processes.