We report the distribution of a cryptographic key, secure from photon number splitting attacks, over 35 km of optical fiber using single photons from an InAs quantum dot emitting ~1.3 microns in a pillar microcavity. Using below GaAs-bandgap optical excitation, we demonstrate suppression of multiphoton emission to 10% of the Poissonian level without detector dark count subtraction. The source is incorporated into a phase encoded interferometric scheme implementing the BB84 protocol for key distribution over standard telecommunication optical fiber. We show a transmission distance advantage over that possible with (length-optimized) uniform intensity weak coherent pulses at 1310 nm in the same system.
@article{arxiv.0710.0565,
title = {Quantum key distribution using a triggered quantum dot source emitting near 1.3 microns},
author = {P. M. Intallura and M. B. Ward and O. Z. Karimov and Z. L. Yuan and P. See and A. J. Shields and P. Atkinson and D. A. Ritchie},
journal= {arXiv preprint arXiv:0710.0565},
year = {2007}
}