OYO BUTURI Vol.86 No.11 (2017)
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Height difference measurement by comparing distant optical lattice clocks

Tetsushi TAKANO1, Masao TAKAMOTO2,3, Yuki KUROISHI4, Hidetoshi KATORI1,2,3

According to Einstein’s theory of relativity, the passage of time depends on gravity. On earth, for two clocks with a height difference of 1 cm, the higher clock runs faster by 1.1×10-18, allowing us to determine the height difference through a comparison of distant clocks, which is called “chronometric leveling”. Here we report on the first demonstration of centimeter-level chronometric leveling by comparing distant optical lattice clocks, located at the University of Tokyo and RIKEN and connected by a 30 km phase-stabilized fiber link. Furthermore, we discuss the future internet of clocks, which may serve as “quantum benchmarks” allowing us to monitor the geopotential variation.

  • 1 Department of Applied Physics, Graduate School of Engineering, The University of Tokyo
  • 2 Quantum Metrology Laboratory, RIKEN
  • 3 Earthquake Research Institute, The University of Tokyo
  • 4 RIKEN Center for Advanced Photonics
OYO BUTURI Vol.86 No.11 p.972 (2017)