Investigation of novel engineering and scientific applications of ultra-precise optical lattice clocks

2020 Fiscal Year Final Research Report

• Project/Area Number: 16H06284
• Research Category: Grant-in-Aid for Specially Promoted Research
• Allocation Type: Single-year Grants
• Review Section: Science and Engineering; Mathematics and Physics
• Research Institution: The University of Tokyo
• Principal Investigator: Katori Hidetoshi 東京大学, 大学院工学系研究科(工学部), 教授 (30233836)
• Co-Investigator(Kenkyū-buntansha): 高本 将男 国立研究開発法人理化学研究所, 開拓研究本部, 専任研究員 (30401144)
• Project Period (FY): 2016-04-26 – 2021-03-31
• Keywords: 光格子時計 / 魔法波長 / 相対論的測地 / 原子時計

Outline of Final Research Achievements

We have experimentally investigated Sr, Yb, Hg, and Cd based clocks to find the most promising atomic element that leads to an ultraprecise clock with 19 digits precision. In particular, we have determined the magic wavelength for Cd atom, tested a “loop closure relation” for the frequency ratio of Sr/Yb/Hg-based clocks to prove the consistency of frequency ratio measurements, and determined the “operational magic condition” for Sr clock. From the viewpoints of controllability of atomic motion, higher-order/ and multipolar polarization effects of atoms, the black-body radiation shift, and maintainability of lasers, we take Sr to be the most favorable atomic candidate and developed transportable clocks. These clocks were transported to Tokyo Skytree, which provided the clocks with a height difference of 450 m. We have tested the gravitational red shift with 5 digits precision, which is competitive to that obtained in space experiments.

Free Research Field

量子エレクトロニクス

Academic Significance and Societal Importance of the Research Achievements

本研究で実証した18桁精度の小型・可搬な光格子時計は、局所位置不変性など相対論検証の実験可能性を一気に広げる。スカイツリーを使った実証実験の成果は、理論家の興味を喚起するとともに、メディアにも大きく取り上げられ、成果のアウトリーチとして有効に機能した。このような可搬時計は、従来手法では困難な大陸間での高精度時計比較を可能とし、SI秒の再定義に貢献する一方、1cmの相対論的測位を可能とする重力ポテンシャル計として機能し、将来の火山学、地震学に新しい観測手段を提供することが期待される。