Cavity quantum electrodynamics (cavity QED) considers the quantum mechanical interaction of emitters located in a cavity with the electromagnetic field in the cavity under circumstances where the quantized nature of the field is important, for example, when the system dynamics changes upon addition or removal of only a single photon [1].The confinement of the light quanta in the cavity results in the enhancement of the coupling between emitter and field, which leads to significant modification of the radiative emitter dynamics.
The emitter dynamics is determined by the balance between the coherent emitter-cavity coupling g and the cavity loss rate g, it can be enhanced and even become reversible in the strong-coupling regime when the energy oscillates back and forth between emitter and cavity in a coherent way. The realization of the strong coupling regime requires the design of cavities with high quality factors Q, but at the same time small mode volume V, since g ∼V−1/2.