# Prospects for strongly coupled atom-photon quantum nodes

## TL;DR

This paper explores the potential of creating strongly coupled atom-photon quantum nodes by trapping cold atoms in microscopic voids within optical waveguides, demonstrating that optimized void shapes can enable strong coupling and high cooperativity.

## Contribution

It introduces a method for trapping cold atoms in microscopic voids in waveguides and shows how shaping these voids can facilitate strong atom-photon coupling with high cooperativity.

## Key findings

- Optimized void shaping reduces optical power loss.
- Strong coupling achievable with cavity formation around voids.
- Cooperativities of ~400 or more are feasible.

## Abstract

We discuss the trapping of cold atoms within microscopic voids drilled perpendicularly through the axis of an optical waveguide. The dimensions of the voids considered are between 1 and 40 optical wavelengths. By simulating light transmission across the voids, we find that appropriate shaping of the voids can substantially reduce the associated loss of optical power. Our results demonstrate that the formation of an optical cavity around such a void could produce strong coupling between the atoms and the guided light. By bringing multiple atoms into a single void and exploiting collective enhancement, cooperativities ~400 or more should be achieveable. The simulations are carried out using a finite difference time domain method. Methods for the production of such a void and the trapping of cold atoms within it are also discussed.