2013/11/30 by Zheshen Zhang, Jacob Mower, Dirk Englund +2
Physics and Astronomy · #quant-ph
paper · pdf · doi:10.1103/physrevlett.112.120506
17 pages, 2 figures
arxiv created 2014/01/23 · arxiv updated 2015/06/17
High-dimensional quantum key distribution (HDQKD) offers the possibility of high secure-key rate with high photon-information efficiency. We consider HDQKD based on the time-energy entanglement produced by spontaneous parametric downconversion, and show that it is secure against collective attacks. Its security rests upon visibility data -- obtained from Franson and conjugate-Franson interferometers -- that probe photon-pair frequency correlations and arrival-time correlations. From these measurements an upper bound can be established on the eavesdropper's Holevo information by translating the Gaussian-state security analysis for continuous-variable quantum key distribution so that it applies to our protocol. We show that visibility data from just the Franson interferometer provides a weaker, but nonetheless useful, secure-key rate lower bound. To handle multiple-pair emissions, we incorporate the decoy-state approach into our protocol. Our results show that over 200 km transmission distance in optical fiber, time-energy entanglement HDQKD could permit a 700 bit/sec secure-key rate, and a photon information efficiency of 2 secure-key bits per photon coincidence in the key-generation phase using receivers with 15% system efficiency.