2006/08/03 by Raul Garcia-Patron, Nicolas J. Cerf
Physics and Astronomy · #quant-ph
paper · pdf · doi:10.1103/physrevlett.97.190503
published as Phys. Rev. Lett. 97, 190503 (2006). · 4 pages, 4 figures
arxiv created 2006/08/03 · arxiv updated 2009/12/01
A fully general approach to the security analysis of continuous-variable quantum key distribution (CV-QKD) is presented. Provided that the quantum channel is estimated via the covariance matrix of the quadratures, Gaussian attacks are shown to be optimal against all eavesdropping strategies, including collective and coherent attacks. The proof is made strikingly simple by combining a physical model of measurement, an entanglement-based description of CV-QKD, and a recent powerful result on the extremality of Gaussian states [Phys. Rev. Lett. 96, 080502 (2006)].