We demonstrate for the first time the feasibility of free space quantum key distribution with continuous variables under real atmospheric conditions. More specifically, we transmit coherent polarization states over a 100m free space channel on the roof of our institute's building. In our scheme, signal and local oscillator are combined in a single spatial mode which auto-compensates atmospheric fluctuations and results in an excellent interference. Furthermore, the local oscillator acts as spatial and spectral filter thus allowing unrestrained daylight operation.
@article{arxiv.0811.4756,
title = {Feasibility of free space quantum key distribution with coherent polarization states},
author = {D. Elser and T. Bartley and B. Heim and Ch. Wittmann and D. Sych and G. Leuchs},
journal= {arXiv preprint arXiv:0811.4756},
year = {2009}
}
Comments
12 pages, 8 figures, extensions in sections 2, 3.1, 3.2 and 4. This is an author-created, un-copyedited version of an article accepted for publication in New Journal of Physics (Special Issue on Quantum Cryptography: Theory and Practice). IOP Publishing Ltd is not responsible for any errors or omissions in this version of the manuscript or any version derived from it