Atomic fountains and optical clocks at SYRTE: status and perspectives

In this article, we report on the work done with the LNE–SYRTE atomic clock ensemble during the last 10 years. We cover the progress made in atomic fountains and in their application to timekeeping. We also cover the development of optical lattice clocks based on strontium and on mercury. We report on tests of fundamental physical laws made with these highly accurate atomic clocks. We also report on work relevant to a future possible redefinition of the SI second.