Description:

Abstract: Atomic clocks based on optical transitions are now capable of measuring time at 18 digits of precision, and beyond. At this level, it becomes challenging to form large-scale timing networks on Earth, due to present-day limits in accounting for the relativistic effects of Earth’s gravity on time. Nevertheless, if measurements between diverse species of atomic clocks can be made at the highest performance, they offer a sensitive probe in the search for physics beyond the Standard Model. I highlight this capability by describing three recent measurements made with the ytterbium optical lattice clock at NIST. First, I detail optical frequency ratio measurements carried out in the Boulder Atomic Clock Network. These measurements utilize ytterbium and strontium optical lattice clocks and the Al+ quantum logic clock, and are exploited in a search for ultralight scalar dark matter. Second, I describe an eight-month long measurement campaign involving the NIST Yb clock and cesium fountain clocks in Europe, used for constraining violations of local position invariance and gravitational coupling to fundamental constants. Finally, I describe a global-scale observatory consisting of optical clocks in Europe, Japan, and NIST. By searching for transient effects in stable optical cavities that are frequency-locked to atomic clock transitions, we place constraints on the coupling of topological dark matter with Standard Model particles.

Andrew Ludlow, National Institute of Standards and Technology

Host: CFP

Keywords: Physics, Center for Fundamental Physics