Resumen:
elected for the April 2009 Vol 9, Issue 4 of Virtual Journal of Quantum Information.American Institute of Physics and the American Physical Societyhttp://www.vjquantuminfo.orgE. Rufeil-Fiori, C. M. Sánchez, F. Y. Oliva, H. M. Pastawski, and P. R. Levstein.Physical Review A, 79, 3, 032324-1-8 (2009).