Additive Extensions of a Quantum Channel
Quantum Physics
2009-02-20 v1
Abstract
We study extensions of a quantum channel whose one-way capacities are described by a single-letter formula. This provides a simple technique for generating powerful upper bounds on the capacities of a general quantum channel. We apply this technique to two qubit channels of particular interest--the depolarizing channel and the channel with independent phase and amplitude noise. Our study of the latter demonstrates that the key rate of BB84 with one-way post-processing and quantum bit error rate q cannot exceed H(1/2-2q(1-q)) - H(2q(1-q)).
Cite
@article{arxiv.0712.2471,
title = {Additive Extensions of a Quantum Channel},
author = {Graeme Smith and John A. Smolin},
journal= {arXiv preprint arXiv:0712.2471},
year = {2009}
}
Comments
6 pages, one figure