Osnabrück 2002 – wissenschaftliches Programm

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Q: Quantenoptik

Q 432: Poster: Quanteninformation

Q 432.8: Poster

Donnerstag, 7. März 2002, 16:30–18:30, Schloss

Secure quantum key sharing with Aharonov states — •Aldo Delgado¹, Gernot Alber¹, and Igor Jex² — ¹Abteilung für Quantenphysik, Universität Ulm, D-89069 Ulm, Germany — ²Department of Physics, FNSPE Czech Technical University Prague, 115 19 Praha, Czech Republic

A new quantum key sharing protocol is presented [1]. It is a generalization of Ekert’s quantum cryptographic protocol [2] to three parties. With this protocol a party can simultaneously create and distribute a random classical key between two other parties in such a way that these two parties have access to this random key only if they share the information that they have received.

Our protocol is based on the use of a total, anti-symmetric three-particle state, a so called Aharonov state. Its security is investigated with respect to some eavesdropping strategies. In particular, it is shown that a local, realistic theory cannot be constructed for a specific choice of measurements so that an eavesdropper, having total control of the measurement devices, cannot simulate this new key sharing protocol with a classical stochastic process.
This work is supported by the DFG within the SPP ‘Quanteninformationsverarbeitung’ and by the DLR. A.D. and I.J. acknowledge support by the DAAD and by the GA of the Czech Republic.

[1] A. Delgado, G. Alber, I. Jex (in preparation).

[2] A. K. Ekert, Phys. Rev. Lett. 67, 661 (1991).