Berlin 2005 – scientific programme

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Q: Quantenoptik und Photonik

Q 3: Poster Quanteninformation, -kommunikation und Quantencomputer

Q 3.25: Poster

Friday, March 4, 2005, 11:00–12:30, Poster HU

Entanglement in a weak coherent pulse protocol — •Johannes Rigas and Norbert Lütkenhaus — University Erlangen-Nürnberg, Institute of Theoretical Physics I, Quantum Information Theory Group

The detection of quantum correlations in the observed data of a QKD protocol is crucial for its security[1]. We investigate the possibilities to detect such correlations in the data of a specific “prepare & measure” protocol: This protocol is implemented in a setup using two polarization-modulated weak coherent pulses with a significant overlap and using a tomographical-complete heterodyning measurement as receiver with data postselection[2].

We derive conditions that verify the underlying quantum correlations. They are based on the knowledge of signal preparation and overlap and purity of the conditional states detected by the receiver.

[1] M. Curty, M. Lewenstein, N. Lütkenhaus: Entanglement as precondition for secure quantum key distribution; Phys. Rev. Lett. 92, 217903 (2004)

[2] S. Lorenz, N. Korolkova, G. Leuchs: Continuous variable quantum key distribution using polarization encoding and post selection; Appl. Phys. B 79, 273-277 (2004)