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Q: Quantenoptik
Q 123: Quantum Communication
Q 123.1: Talk
Monday, March 4, 2002, 16:30–16:45, HS 11/215
Photon Number Statistics and Quantum Key Distribution — •Norbert Lütkenhaus1, John Calsamiglia2, Mika Jahma2, and Stephen M. Barnett3 — 1Quantum information theory group, ZEMO, University Erlangen-Nürnberg — 2Helsinki Institute of Physics, Finland — 3Department of Physics and Applied Physics, Strathclyde University, Glasgow, UK
Quantum Key Distribution can be implemented with simple signal sources such as weak laser pulses with a Poissonian photon number distribution. The limits of protocols with polarised light pulses are characterised via the Photon-Number Splitting Attack (PNS). [1] In this attack, an eavesdropper splits off one photon from the light pulse and stores it. Eventually, this photon will reveal the complete information hidden in the signal without disturbing the polarisation of the remaining pulse. We show that we can extend this attack such that it mimics a typical lossy channel and produces again a Poissonian photon number statistics. In a second line we show that the PNS attack can be approximated by tools of linear optics. [2]
[1] G. Brassard, N.L., T. Mor, B. Sanders, Phys. Rev. Lett., Vol. 85, 1330–1333 (2000).
[2] J. Calsamiglia, S. M. Barnett, N.L., Phys. Rev. A, Vol. 65, 012312 (2002).