Frankfurt 2006 – scientific programme

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Q: Quantenoptik und Photonik

Q 76: Poster Quantenkommunikation

Q 76.7: Poster

Thursday, March 16, 2006, 16:30–18:30, Labsaal

Secret key rate in tomographic quantum cryptography with a finite number of signals — •Tim Meyer, Matthias Kleinmann, Hermann Kampermann, and Dagmar Bruß — Institut für theoretische Physik, Universität Düsseldorf, Universtätsstr. 1, 40225 Düsseldorf

We calculate the minimum key length achievable with the “tomographic key distribution protocol” ∖Zitat{1}{D. Bruß et. al., PRL 91, 097901 (2003)}. This protocol is an extension of the six-state protocol, with the main twist that Alice and Bob do not discard events, in which they measured in a different basis, but use this data to do state tomography. We use recent results by ∖Zitat{2}{R. Renner, N. Gisin, and B. Kraus, PRA 72, 012332 (2005)} where bounds on the secret key rate for the limiting case of an infinite number of signals were derived. In contrast to their work, we explicitly calculate the key length for a finite number of signals, without taking the asymptotic limit. Thus, our method is useful for a realistic scenario of quantum key distribution.