Frequency ratio measurements at 18-digit accuracy using an optical clock network.

  title={Frequency ratio measurements at 18-digit accuracy using an optical clock network.},
  volume={591 7851},
  • Published 1 March 2021
  • Physics
  • Nature
Atomic clocks are vital in a wide array of technologies and experiments, including tests of fundamental physics1. Clocks operating at optical frequencies have now demonstrated fractional stability and reproducibility at the 10-18 level, two orders of magnitude beyond their microwave predecessors2. Frequency ratio measurements between optical clocks are the basis for many of the applications that take advantage of this remarkable precision. However, the highest reported accuracy for frequency… 
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