A Single Atom as a Mirror of an Optical Cavity

TL;DR

This paper demonstrates that a single cold ion can act as a mirror in a quantum electrodynamic system, significantly altering laser fields and enabling potential quantum memory applications for single photons.

Contribution

It introduces a novel regime where a single atom modifies electromagnetic modes, functioning as a mirror in a cavity, with implications for quantum memory technology.

Findings

Single ion acts as a mirror in a quantum electrodynamic system

Significant alteration of laser field amplitude due to the ion

Potential application as a quantum memory for single photons

Abstract

By tightly focussing a laser field onto a single cold ion trapped in front of a far-distant dielectric mirror, we could observe a quantum electrodynamic effect whereby the ion behaves as the optical mirror of a Fabry-P\'erot cavity. We show that the amplitude of the laser field is significantly altered due to a modification of the electromagnetic mode structure around the atom in a novel regime in which the laser intensity is already changed by the atom alone. e propose a direct application of this system as a quantum memory for single photons.