1Faculty of Informatics, Masaryk University, Botanická 68a, 602 00 Brno, Czech Republic
2Institute of Physics, Slovak Academy of Sciences, Dúbravská cesta 9, 842 28 Bratislava, Slovakia
3Department of Physics and Astronomy, Hunter College, CUNY, 695 Park Avenue, New York, New York 10021
4Institut für Mathematische Physik, TU Braunschweig, Mendelssohnstraße 3, 38304 Braunschweig, Germany