1. Institute for Quantum Optics and Quantum Information (IQOQI-Vienna), Austrian Academy of Sciences, 1090 Vienna, Austria
2. Faculty of Physics, University of Vienna, 1090 Vienna, Austria
3. Facoltà indipendente di Gandria, 6978 Gandria, Switzerland
4. Department of Computer Science, University of Maryland, College Park, Maryland 20742, USA
5. School of Mathematics and Computer Science, Institute of Business Administration, Karachi, Pakistan