Cavity quantum electrodynamics and chiral quantum optics

Cavity quantum electrodynamics (CQED) investigates the interaction between light confined in a resonator and particles, such as atoms. In recent years, CQED experiments have reached the optical domain resulting in many interesting applications in the realm of quantum information processing. For many of these application it is necessary to overcome limitations imposed by photon loss. In this context whispering-gallery mode (WGM) resonators have obtained significant interest. Besides their small mode volume and their ultra high quality, they also exhibit favorable polarization properties that give rise to chiral light--matter interaction. In this chapter, we will discuss the origin and the consequences of these chiral features and we review recent achievements in this area.