The Iqloc II team has published their paper detailing their dynamical decoupling realization in Ca+ to enigineer an artifical clock transition with reduced systematic shifts on the arxive, Congratulations!
Abstract: We present the experimental realization of a continuous dynamical decoupling scheme which sup- presses leading frequency shifts in a multi-ion frequency reference based on 40Ca+. By near-resonant magnetic coupling of the 2S1/2 and 2D5/2 Zeeman sub-levels using radio-frequency dressing fields, engineered transitions with reduced sensitivity to magnetic-field fluctuations are obtained. A second stage detuned dressing field reduces the influence of amplitude noise in the first stage driving fields and decreases 2nd-rank tensor shifts, such as the electric quadrupole shift. Suppression of the quadratic dependence of the quadrupole shift to 3(2) mHz/µm2 and coherence times of 290(20) ms on the optical transition are demonstrated even within a laboratory environment with significant magnetic field noise. Besides removing inhomogeneous line shifts in multi-ion clocks, the demonstrated dynamical decoupling technique may find applications in quantum computing and simulation with trapped ions by a tailored design of decoherence-free subspaces.