Düsseldorf 2007 – wissenschaftliches Programm

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Q: Fachverband Quantenoptik und Photonik

Q 6: Quanteninformation (Photonen und nichtklassisches Licht II)

Q 6.3: Vortrag

Montag, 19. März 2007, 14:30–14:45, 5L

A Narrow-Band Single-Photon Source — •Florian Wolfgramm, Matthias Scholz, and Oliver Benson — Humboldt-Universität zu Berlin, Institut für Physik, AG Nanooptik, Hausvogteiplatz 5-7, 10117 Berlin

Recently, there has been extensive progress on the storage of single photons. Most storage schemes rely on the matching of photons to the bandwidth of atomic resonances. This feature is not fulfilled by single-photon sources based on quantum dots, parametric down-conversion, molecules, or NV-centers in diamond.

While narrow bandwidths have been achieved using single stored atoms or ions, a more simple approach takes advantage of the narrow-band output of Optical Parametric Oscillators (OPO), where the down-conversion bandwidth is reduced to that of the cavity. Operating the OPO far below threshold, a heralded single-photon source can be realized with the idler photon as the trigger. The feasibility of such a scheme has been proven for a type-I OPO. Type-II down-conversion has the advantage of perpendicular polarization and has been implemented without active stabilization of the cavity. Our approach with type-II phase-matching avoids the problem of stabilizing the cavity for signal and idler. Instead, we are separating the idler by intra-cavity beamsplitters, stabilizing the cavity only for the signal. With this setup we were able to generate heralded single-photon states with a bandwidth of below 100 MHz at the D1-transition of cesium. Such a narrow-band single-photon source could find wide applications in the field of quantum information processing.