Solaro Cyrille, Meyer Steffen, Fisher Karin, Berengut Julian C, Fuchs Elina, Drewsen Michael
Department of Physics and Astronomy, Aarhus University, DK-8000 Aarhus C, Denmark.
School of Physics, University of New South Wales, Sydney, New South Wales 2052, Australia.
Phys Rev Lett. 2020 Sep 18;125(12):123003. doi: 10.1103/PhysRevLett.125.123003.
We perform high-resolution spectroscopy of the 3d ^{2}D_{3/2}-3d ^{2}D_{5/2} interval in all stable even isotopes of ^{A}Ca^{+} (A=40, 42, 44, 46, and 48) with an accuracy of ∼20 Hz using direct frequency-comb Raman spectroscopy. Combining these data with isotope shift measurements of the 4s ^{2}S_{1/2}↔3d ^{2}D_{5/2} transition, we carry out a King plot analysis with unprecedented sensitivity to coupling between electrons and neutrons by bosons beyond the standard model. Furthermore, we estimate the sensitivity to such bosons from equivalent spectroscopy in Ba^{+} and Yb^{+}. Finally, the data yield isotope shifts of the 4s ^{2}S_{1/2}↔3d ^{2}D_{3/2} transition at 10 parts per billion through combination with recent data of Knollmann, Patel, and Doret [Phys. Rev. A 100, 022514 (2019)PLRAAN2469-992610.1103/PhysRevA.100.022514].
