# Fabrication of a centimeter-long cavity on a nanofiber for cavity QED

## TL;DR

This paper demonstrates the fabrication of a centimeter-long nanofiber cavity with high finesse and transmission, enabling strong-coupling cavity QED and applications in quantum optics.

## Contribution

It introduces a femtosecond laser ablation method to create long nanofiber cavities suitable for quantum electrodynamics experiments.

## Key findings

- Cavity finesse ranges from 200 to 400.
- Transmission remains between 40% and 85%.
- Enables strong-coupling regime for single atoms.

## Abstract

We report the fabrication of a 1.2 cm long cavity directly on a nanofiber using femtosecond laser ablation. The cavity modes with finesse value in the range 200-400 can still maintain the transmission between 40-60%, which can enable "strong-coupling" regime of cavity QED for a single atom trapped 200 nm away from the fiber surface. For such cavity modes, we estimate the one-pass intra-cavity transmission to be 99.53%. Other cavity modes, which can enable high cooperativity in the range 3-10, show transmission over 60-85% and are suitable for fiber-based single photon sources and quantum nonlinear optics in the "Purcell" regime.