Unconditional security of continuous-variable quantum key distribution
Abstract
The unconditional security of continuous-variable quantum key distribution is established for all schemes based on the estimation of the channel loss and excess noise. It is proved that, in the limit of large keys, Gaussian attacks are asymptotically optimal among the most general (coherent) attacks, where the transmission is tapped using arbitrary ancillas and stored in a quantum memory as a whole. Then, it is shown that the previously derived bounds on the achievable secret key rates against collective attacks remain asymptotically valid for arbitrary coherent attacks.
Cite
@article{arxiv.0809.2252,
title = {Unconditional security of continuous-variable quantum key distribution},
author = {Anthony Leverrier and Evgueni Karpov and Philippe Grangier and Nicolas J. Cerf},
journal= {arXiv preprint arXiv:0809.2252},
year = {2010}
}
Comments
This paper has been withdrawn by the authors. The approach investigated in this preprint fails for the following reason: for a fixed $n$, the $\epsilon$-smooth min-entropy is a continuous function of $\epsilon$ for a given $n$-mode state but the Lipschitz constant of the function increases with $n$. As a consequence, one cannot interchange the limits $\epsilon$ tending to 0 with $n$ tending to infinity. Note, however, that an unconditional security proof of continuous-variable quantum key distribution was established in Phys. Rev. Lett. 102, 110504 (2009) (preprint arXiv:0809.2243)