We demonstrate highly efficient switching of optical signals between two optical fibers controlled by a single atom. The key element of our experiment is a whispering-gallery mode bottle microresonator, which is coupled to a single atom and interfaced by two tapered fiber couplers. Even in the presence of the coupling fibers, the atom--resonator system reaches the strong coupling regime of cavity quantum electrodynamics (CQED), leading to a vacuum Rabi splitting in the excitation spectrum. We systematically investigate the switching efficiency of our system, i.e., the probability that the CQED fiber-optical switch redirects the light into the desired output. We obtain a large redirection efficiency reaching a raw fidelity of more than 60% without post-selection.
@article{arxiv.1306.1357,
title = {Fiber-optical switch controlled by a single atom},
author = {Danny O'Shea and Christian Junge and Jürgen Volz and Arno Rauschenbeutel},
journal= {arXiv preprint arXiv:1306.1357},
year = {2015}
}