Institution: | a School of Communication and Information Technology, Royal Institute of Technology (KTH), Electrum 229, SE-164 40 Kista, Sweden b Departamento de Óptica, Facultad de Física, Universidad Complutense, 28040 Madrid, Spain c Departamento de Física, Universidad de Guadalajara, 44420 Guadalajara, Jalisco, Mexico d Centre for Advanced Quantum Physics, University of Bucharest, PO Box MG-11, R-077125, Bucharest-M?gurele, Romania |