Quantum key distribution using quantum-correlated photon sources
Advanced Telecommunications and Quantum Electronics Research Centre, University of
Canberra, Canberra ACT 2601, Australia
Published online: 15 February 2002
Quantum key exchanges using weak coherent (Poissonian) single-photon sources are open to attack by a variety of eavesdropping techniques. Quantum-correlated photon sources provide a means of flagging potentially insecure multiple-photon emissions and thus extending the secure quantum key channel capacity and the secure key distribution range. We present indicative photon-counting statistics for a fully correlated Poissonian multibeam photon source in which the transmitted beam is conditioned by photon number measurements on the remaining beams with non-ideal multiphoton counters. We show that significant rejection of insecure photon pulses from a twin-beam source cannot be obtained with a detector having a realistic quantum efficiency. However quantum-correlated (quadruplet or octuplet) multiplet photon sources conditioned by high efficiency multiphoton counters could provide large improvements in the secure channel capacity and the secure distribution range of high loss systems such as those using the low earth orbit satellite links proposed for global quantum key distribution.
PACS: 03.67.Dd – Quantum cryptography / 02.50.Fz – Stochastic analysis / 42.50.Lc – Quantum fluctuations, quantum noise, and quantum jumps
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag, 2002