In quantum information systems it is of particular interest to consider the best way in which to use the non-classical resources consumed by that system. Quantum communication protocols are integral to quantum information systems and are amongst the most promising near-term applications of quantum information science. Here we show that a multiplexed, digital quantum communications system supported by comb of vacuum squeezing has a greater channel capacity per photon than a source of broadband squeezing with the same analogue bandwidth. We report on the time-resolved, simultaneous observation of the first dozen teeth in a 2.4 GHz comb of vacuum squeezing produced by a sub-threshold OPO, as required for such a quantum communications channel. We also demonstrate multiplexed communication on that channel.
@article{arxiv.1002.4068,
title = {Multiplexed communication over a high-speed quantum channel},
author = {M. Heurs and J. G. Webb and A. E. Dunlop and C. C. Harb and T. C. Ralph and E. H. Huntington},
journal= {arXiv preprint arXiv:1002.4068},
year = {2015}
}