1. Graduate School of Engineering and Science, Shibaura Institute of Technology, Fukasaku 307, Saitama 337-8570, Japan
2. National Synchrotron Radiation Research Center, Hsinchu 30076, Taiwan
3. RIKEN SPring-8 Center, 1-1-1, Koto, Sayo-cho, Sayo-gun, Hyogo 679-5148, Japan
4. Department of Physics, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
5. Center for Quantum Science and Technology and Department of Physics, National Tsing Hua University, Hsinchu 30013, Taiwan
6. Department of Applied Physics, Waseda University, Shinjuku, Tokyo 169-8555, Japan