Coherent one photon pulses are sent with four possible time delays with respect to a reference. Ambiguity of the photon time detection resulting from pulses overlap combined with interferometric measurement allows for secure key exchange.
@article{arxiv.quant-ph/0309139,
title = {4 states protocol for time coding quantum key distribution},
author = {Thierry Debuisschert and William Boucher},
journal= {arXiv preprint arXiv:quant-ph/0309139},
year = {2007}
}
Comments
2 pages, 2 figures, Proceedings from the QELS conference, june 1-6, 2003, QTuB2