“Cavity quantum electrodynamics” is a sub-field of quantum optics. Speaking at the EPL symposium, “Physics In Our Times” held last week at the Fondation Del Duca de l’Institut de France, Paris Professor Serge Haroche from the Collège de France and the École Normale Supérieure in Paris, explained how he and his colleagues manipulate and control single atoms and single photons interacting in a cavity, which is a box made of highly reflecting walls.