Abstract:Quantum key distribution with pulsed heralded single photon source was performed over 40 km of fiber for the first time to our knowledge. QBER was measured to be 4.23% suggesting security against unconditional attack. 58-60 (1986). 19. Using a model presented in reference [10,11,16], we estimated the average number of photon pairs μ at the crystal output to be 0.168 at the maximum pump power (195 mW), and 3 pairs event probability at the crystal ouput to be a fraction equal to 0.056 of the two pairs generation probability for this pump power. 20. C. H. Bennett, "Quantum cryptography using any two nonorthogonal states," Phys. Rev. Lett. 68, 3121-3124 (1992)

Heralding of single photon at 1550 nm from pump pulsed non degenerate spontaneous parametric downconversion is demonstrated. P(1) and P(2) of our source are 0.1871 and 2.4 µ 10 -3 respectively. Triggering of our source is 2.16 µ 10 5 trigger.s -1 . This source may be used in QKD system.

In this paper, for the decoy state method using a finite number of decoy light intensities, we present an improved upper and lower bounds for the asymptotic yield y n for n-photon states. In particular if all the light intensities are less than or equal to one, they are not only a lower or upper bound, but in fact are the exact minimum or maximum.

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