1. Division of Information and Media Science, Graduate School of Science and Technology, Kobe University, Rokkodai, Kobe 657-8501
2. Department of Physics, Faculty of Science, Kobe University, Rokkodai, Kobe 657-8501
3. Department of Informatics, Faculty of Cross-Cultural Studies, Kobe University, Tsurukabuto, Kobe 657-8501
4. Department of Applied Physics, University of Tokyo, Bunkyo-ku, Tokyo 113-8656
5. Institut für Theoretische Physik, Universität Hannover, 30167 Hannover, Germany