ECAMP 15

Optical clocks have now surpassed the Cs based primary frequency standards by two orders of magnitude. The working groups of the Consultative Committee for Time and Frequency are now evaluating the different options for the redefinition, expected to take place in the early 2030s. In this paper, I present one of these options, that proposes to define the second based on the average of several transitions. Such a definition would allow to take advantage of the variety of optical frequency standards available today. We show how this definition can be realized, and give an analysis of its advantages and drawbacks.