 Cavity quantum electrodynamics

Cavity quantum electrodynamics studies chemical atoms or related quantum emitters interacting with quantized electromagnetic field modes confined by a cavity. Confinement changes the available mode structure and can strengthen a single excitation's coupling to the emitter. The interaction rate, cavity loss and emitter decoherence determine whether coherent exchange can be resolved.

Near resonance, an chemical atom and mode can exchange excitation; far from resonance, dispersive atom-cavity coupling produces state- and photon-number-dependent shifts. In the microwave photon-box experiments described in the authored lecture, chemical atoms provide repeated nondestructive probes of a long-lived field, allowing photon-number jumps and nonclassical field states to be studied.^[ref] A cavity's presence alone does not establish strong coupling or a particular nonclassical state.

Cavity quantum electrodynamics (cavity QED) is a field of physics that studies the interactions between light (photons) and matter (typically atoms or quantum dots) confined in a small cavity or resonator. The essential idea is to control and enhance the interaction between light and matter by using a cavity, which can trap photons and force them to interact more strongly with the quantum systems placed inside.