Hyperfine Averaging by Dynamic Decoupling in a Multi-Ion Lutetium Clock

We propose and experimentally demonstrate a scheme that realizes hyperfine averaging during a Ramsey interrogation of a clock transition. The method eliminates the need to average over multiple optical transitions, reduces the sensitivity of the clock to its environment, and reduces inhomogeneous broadening in a multi-ion clock. The method is compatible with autobalanced Ramsey spectroscopy, which facilitates the elimination of residual shifts due to imperfect implementation and ac stark shifts from the optical probe. We demonstrate the scheme using correlation spectroscopy of the ¹S₀↔³D₁ clock transition in a three-ion Lu⁺ clock. From the demonstration we are able to provide a measurement of the ³D₁ quadrupole moment, Θ(³D₁)=0.634(9)ea₀².