In quantum communication via noisy channels, the error probability scales exponentially with the length of the channel. We present a scheme of a quantum repeater that overcomes this limitation. The central idea is to connect a string of (imperfect) entangled pairs of particles by using a novel nested purification protocol, thereby creating a single distant pair of high fidelity. The scheme tolerates general errors on the percent level.
@article{arxiv.quant-ph/9803056,
title = {Quantum repeaters for communication},
author = {H. -J. Briegel and W. Dür and J. I. Cirac and P. Zoller},
journal= {arXiv preprint arXiv:quant-ph/9803056},
year = {2007}
}