1. Space‐Time Engineering Research Team RIKEN center for Advanced Photonics 2‐1 Hirosawa Wako‐shi Saitama 351‐0198 Japan
2. Quantum Metrology Laboratory, RIKEN 2‐1 Hirosawa Wako‐shi Saitama 351‐0198 Japan
3. Department of Applied Physics Fukuoka University 8‐19‐1 Nanakuma Jonan‐ku Fukuoka 814‐0180 Japan
4. Department of Applied Physics Graduate School of Engineering The University of Tokyo 2‐11‐16 Yayoi Bunkyo‐ku Tokyo 113‐8656 Japan
5. Citizen Watch Co., Ltd. 840 Simotomi Tokorozawa‐shi Saitama 359‐8511 Japan
6. Institute of Space and Astronautical Science Japan Aerospace Exploration Agency 3‐1‐1 Yoshinodai, Chuo‐ku Sagamihara‐shi Kanagawa 252‐5210 Japan
7. Shimadzu Corporation 3‐9‐4 Hikaridai, Seika‐cho Soraku‐gun Kyoto 619‐0237 Japan
8. Equos Research Co., Ltd. 1‐18‐13 Sotokanda Chiyoda‐ku Tokyo 101‐0021 Japan