Two-cavity mediated photon-pair emission by a single atom

Single atoms coupled to high finesse optical cavities provide a powerful platform for quantum information processing, in which photonic qubits can be efficiently generated, stored and processed. In recent years the attention is focused in increasing both the number of emitters that are strongly coupled to the cavity, and the number of cavity modes that are coupled to the emitter. Miniaturized fiber cavities make it possible that multiple independent resonators are coupled to the same emitter in the high atom-photon cooperativity regime. Here we report on a source based on a single three-level atom coupled to two optical fiber-cavities in a ladder configuration. We efficiently generate photon pairs and study their temporal correlation properties. We also study theoretically the regime where both cavities are strongly coupled to the atom. In this parameter regime we observe that an atom in the upper state can be transferred to the ground state without populating the intermediate state, while generating photons in both cavities. Such a process is analogous to STIRAP but mediated by the vacuum field in both cavities. We study the properties of the cavity light fields and consider parameters that are feasible in order to observe this effect in an experiment.