12:00 - 13:00
Optical lattice clocks at NPL
Optical lattice clocks have demonstrated accuracy and stability at the 18th decimal place, matching or surpassing the performance of any other atomic clock to date. As a result, optical lattice clocks are seen as a leading candidate for a future redefinition of the SI second. Less obviously, by comparing these clocks and monitoring for tiny fluctuations in the measured passage of time, we can measure the effects of gravity and probe for new physics beyond the standard model. In this talk I introduce the two strontium optical lattice clocks at the National Physical Laboratory, their operating principles, and the limitations on their accuracy and stability. I discuss comparisons of the NPL atomic clocks against other very accurate clocks in Paris and Braunschweig, and how these comparisons have been used as tests of relativity and variations of fundamental constants. Finally, I discuss recent results achieved with NPL's latest optical lattice clock, in which we demonstrate a new scheme of cavity-based non-destructive detection, thus realising an important step towards spin-squeezed optical lattice clocks with unprecedented frequency stability.