title: Two-photon gateway in one-atom cavity quantum electrodynamics.
abstract: Single atoms absorb and emit light from a resonant laser beam photon by photon. We show that a single atom strongly coupled to an optical cavity can absorb and emit resonant photons in pairs. The effect is observed in a photon correlation experiment on the light transmitted through the cavity. We find that the atom-cavity system transforms a random stream of input photons into a correlated stream of output photons, thereby acting as a two-photon gateway. The phenomenon has its origin in the quantum anharmonicity of the energy structure of the atom-cavity system. Future applications could include the controlled interaction of two photons by means of one atom.
authors.affiliation: Max-Planck-Institut für Quantenoptik, Hans-Kopfermann-Strasse 1, D-85748 Garching, Germany.
authors.forename: A
authors.initials: A
authors.lastname: Kubanek
authors.forename: A
authors.initials: A
authors.lastname: Ourjoumtsev
authors.forename: I
authors.initials: I
authors.lastname: Schuster
authors.forename: M
authors.initials: M
authors.lastname: Koch
authors.forename: P W H
authors.initials: PW
authors.lastname: Pinkse
authors.forename: K
authors.initials: K
authors.lastname: Murr
authors.forename: G
authors.initials: G
authors.lastname: Rempe