Düsseldorf 2007 – scientific programme

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Q: Fachverband Quantenoptik und Photonik

Q 47: Quanteninformation (Quantenkommunikation)

Q 47.5: Talk

Wednesday, March 21, 2007, 17:30–17:45, 5L

Photon Number Statistics of Waveguided Parametric Downconversion — •Malte Avenhaus, Andreas Eckstein, and Christine Silberhorn — Max-Planck-Nachwuchsgruppe für Integrierte Quantenoptik, Erlangen, Germany

Quantum cryptography requires precise knowledge about the quantum states which are communicated over a quantum channel. Especially, the photon number distribution of the quantum light source characterizes the security and performance of practical systems. By detecting impinging photons on highly efficient APDs in Geiger mode, one can only gain binary information, but no resolution regarding actual photon numbers. In our experiment, we use a time multiplexing device distributing photons randomly over several temporal slots. For reconstruction of the actual photon statistics, one needs to take into account losses and the possibilities of n photons being observed in m temporal slots.

We investigate the properties of photon number statistics from a Type-II parametric downconversion (PDC) processes at different pump powers. The resulting statistics from different experimental configurations are compared against correlated thermal and Poissonian distributions, which can be expected for PDC sources.