1. Department of Physics, University of Tokyo, Bunkyo, Tokyo 113-0033, Japan
2. Nomura Securities Co., Ltd., Chuo, Tokyo 103-8011, Japan
3. Department of Physics, Gakushuin University, Toshima, Tokyo 171-8588, Japan
4. Trans-scale Quantum Science Institute, University of Tokyo, Bunkyo, Tokyo 113-0033, Japan