Osnabrück 2002 – scientific programme

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Q: Quantenoptik

Q 313: Quanteneffekte I

Q 313.3: Talk

Wednesday, March 6, 2002, 14:45–15:00, HS 01/E02

Photon antibunching and bunching in a strongly coupled atom-cavity system — •Markus Hennrich, Axel Kuhn, and Gerhard Rempe — Max-Planck-Institut für Quantenoptik, D-85748 Garching

An essential element for quantum cryptography and quantum communication is the availability of a deterministic single-photon source. Lately, several sources based on the excitation of, e.g., a single quantum dot, a single molecule, or a colour centre in diamond have been demonstrated. All of them are suitable to emit a photon upon an external trigger event. However, the photon is emitted into many modes of the radiation field.

Our approach uses the coupling of a rubidium atom to one vacuum mode of a high-finesse cavity and generates photons of well-defined frequency and direction using a Raman process in a lambda-type three level system. A pump laser acts as the exciting laser while the cavity is stimulating the photon emission. Every atom falling through the cavity can emit one photon upon a Raman transfer [1]. To repeat the photon emission a recycling laser has been added that is pumping the atom back to its initial state. In the experiment both pump and recycling lasers were continuously acting on the atom. Thus a single atom emits a burst of photons that are antibunched due to the limited recycling time. If the flux of atoms through the cavity is increased the antibunching disappears and instead a bunching of photons is detected. This is a sign of amplification by stimulated emission of radiation into the cavity, and in this sense our system acts as a Raman laser with a medium of less than 10 atoms.

[1] M. Hennrich et al., Phys.Rev.Lett. 85, 4872-4875 (2000)