Cavity quantum electrodynamics with a single molecule: Purcell enhancement, strong coupling and single-photon nonlinearity

Control of light-matter coupling at the quantum level is an enabling technique for many emerging quantum technologies. This tutorial describes recent advances in achieving efficient coupling of light with a single molecule using an optical Fabry-Perot microcavity. We demonstrate that the efficient cavity-molecule coupling converts the molecule to an effective two-level system. In this regime, a single molecule can act as a nearly perfect reflecting mirror and exhibits optical nonlinearity at the ultimate level of single photons.