Nicolas Sangouard,* Christoph Simon, Nicolas Gisin, Julien Laurat, Rosa Tualle-Brouri, and Philippe Grangier Group of Applied Physics-Optics, University of Geneva, CH-1211 Geneva 4, Switzerland Matériaux et Phènomènes Quantiques, CNRS UMR 7162, Université Paris Diderot, 75013 Paris France Institute for Quantum Information Science and Department of Physics and Astronomy, University of Calgary, C...