On a definition of the SI second with a set of optical clock transitions

  title={On a definition of the SI second with a set of optical clock transitions},
  author={J{\'e}r{\^o}me Lodewyck},
  • J. Lodewyck
  • Published 16 September 2019
  • Physics
  • Metrologia
The current SI second based on the atomic hyperfine transition in the ground state of 133Cs is expected to be replaced by a new definition based on optical frequency standards, whose estimated uncertainty has now been established two orders of magnitude lower than the accuracy of the best Cs primary standards. However, such a redefinition of the second is hindered by the fact that many atomic species are potential contenders to become the new primary frequency standard. In this paper, we… 
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  • T. Ido
  • Physics
    IEEE Transactions on Instrumentation and Measurement
  • 2019
How optical frequency standards have made progress to surpass microwave frequency standards and the level they are presently at are shown.