Fiber-optical switch controlled by a single atom

TL;DR

This paper demonstrates a highly efficient fiber-optical switch controlled by a single atom using a whispering-gallery mode microresonator, achieving over 60% fidelity in directing light, advancing quantum photonic switching technology.

Contribution

It introduces a novel single-atom controlled optical switch with high efficiency using a microresonator in the strong coupling regime.

Findings

Achieved over 60% raw fidelity in light redirection.

Demonstrated strong coupling regime with atom-resonator system.

System operates effectively without post-selection.

Abstract

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.