1. Department of Physics, Tokyo Metropolitan University, Hachioji, Tokyo 192-0397, Japan
2. Faculty of Engineering, Hokkaido University, Sapporo 060-8628, Japan
3. Graduate School of Advanced Science and Engineering, Hiroshima University, Higashihiroshima, Hiroshima 739-8526, Japan
4. National Metrology Institute of Japan (NMIJ), National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Ibaraki 305-8565, Japan