Our paper "Coherent Excitation of the Highly Forbidden Electric Octupole Transition in 172Yb+" is published in Physical Review Letters

We demonstrated for the first time coherent excitation of the octupole transition near 467nm in a single 172Yb+ ion, which is a core requirement for a scalable test of Local Lorentz invariance using the electronic F-state manifold.  The large degree of control over the magnetic environment and laser stability enabled us to determine the absolute frequency of the transition to 2.2 Hz absolute uncertainty. In addition, we determined the absolute frequency of the near-411nm quadrupole transition to 4.4 Hz uncertainty. The frequency measurements improve the previously published literature values by at least 5 orders of magnitude. We aim to extend these measurements to other even-numbered isotopes of Yb+ ions for finding potential anomalies in isotope-shifts, which can be used to identify potential dark matter candidates.
You can find the full paper here.