Quantum cryptography and long distance Bell experiments: How to control decoherence

Abstract

Several mechanisms that affect one and two photon coherence in optical fibers and their remedies are discussed. The results are illustrated on quantum cryptography experiments and on long distance Bell inequality tests.

To appear in the proceedings of the workshop on "Decoherence" organised by the ZIF in Bielefeld, October 1998. 6 pages + 5 figures