Efficient routing of single photons by one atom and a microtoroidal cavity

TL;DR

This paper demonstrates a highly efficient quantum router that uses a microtoroidal cavity and a single Cesium atom to direct single photons with robustness against positional and power variations.

Contribution

It introduces a novel photon routing system employing a microtoroidal cavity and single atom, achieving high efficiency and robustness in photon sorting.

Findings

High-efficiency photon routing demonstrated

Photon antibunching observed in reflected light

System robust against atomic position and input power variations

Abstract

Single photons from a coherent input are efficiently redirected to a separate output by way of a fiber-coupled microtoroidal cavity interacting with individual Cesium atoms. By operating in an overcoupled regime for the input-output to a tapered fiber, our system functions as a quantum router with high efficiency for photon sorting. Single photons are reflected and excess photons transmitted, as confirmed by observations of photon antibunching (bunching) for the reflected (transmitted) light. Our photon router is robust against large variations of atomic position and input power, with the observed photon antibunching persisting for intracavity photon number 0.03 \lesssim n \lesssim 0.7.