Hamburg 2009 – scientific programme

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Q: Fachverband Quantenoptik und Photonik

Q 30: Poster II

Q 30.33: Poster

Tuesday, March 3, 2009, 16:30–19:00, VMP 9 Poster

Quantum Key Distribution with passive selection of decoy states — •Felix Just, Malte Avenhaus, Katiuscia Cassemiro, and Christine Silberhorn — Max-Planck-Research Group Günther-Scharowsky-Straße 1 / Bau 24 D-91058 Erlangen

Quantum Decoy protocols promise an alternative way for secure quantum key distribution (QKD) without the necessity of true single photon sources. In order to implement a decoy QKD scheme we investigate the use of a photon source based on parametric down conversion in a periodically poled KTP waveguide. Our goal is the implementation of a highly non-degenerated downconversion process. For decoy cryptography schemes it is crucial to have detailed information about the photon pair statistics of the source. For this purpose the signal photon should be in a wavelength regime where the detection efficiency is optimal. Hence, Si-APDs are used in a time multiplexing detection setup for efficient estimation of photon number statistics. Since the idler photon is intended for the key distribution via a telecommunication fiber network, the respective wavelength constitutes an obvious choice to minimize transmission losses. This in turn requires detection by an InGaAs-APD. Different grating periods on our waveguide chip provide the opportunity of tuning signal and idler wavelength for optimal detection and transmission.