This project will investigate laser-cooled trapped ions as the reference for a next generation of optical clocks of the highest accuracy. While today’s most precise optical clocks with trapped ions are based on single ions, this project will investigate large ensembles of ions in a Coulomb-coupled solid-like state. The multi-ion approach will provide higher signal-to-noise for clocks of improved stability, the sensitivity to investigate small frequency shifts caused by collisions with neutral particles or interactions between the ions, and the opportunity to study new kinds of reference transitions for clocks, specifically the 229Th nuclear transition and
transitions in highly charged ions.