An improved "plug & play" interferometric system for quantum key distribution is presented. Self-alignment and compensation of birefringence remain, while limitations due to reflections are overcome. Original electronics implementing the BB84 protocol makes adjustment simple. Key creation with 0.1 photon per pulse at a rate of 325 Hz with a 2.9 percent QBER - corresponding to a net rate of 210Hz - over a 23 Km installed cable was performed.
@article{arxiv.quant-ph/9812052,
title = {Automated 'plug & play' quantum key distribution},
author = {G. Ribordy and J. -D. Gautier and N. Gisin and O. Guinnard and H. Zbinden},
journal= {arXiv preprint arXiv:quant-ph/9812052},
year = {2007}
}