[1] Univ Fed Sao Carlos, Dept Fis, POB 676, BR-13565905 Sao Carlos, SP, Brazil
[2] Stockholm Univ, Dept Phys, S-10691 Stockholm, Sweden
[3] Univ Cote Azur, Inst Phys Nice, CNRS, F-06560 Valbonne, France
[4] Austrian Acad Sci, Inst Quantum Opt & Quantum Informat, Vienna, Austria
[5] CALTECH, Div Phys Math & Astron, Pasadena, CA 91125 USA