Erratum: Improved Isotope-Shift-Based Bounds on Bosons beyond the Standard Model through Measurements of the ${}^2{\mathrm{D}}_{3/2}-{{}^2\mathrm{D}}_{5/2}$ Interval in ${\mathrm{Ca}}^{+}$ [Phys. Rev. Lett. 125, 123003 (2020)]

Figure 1

Schematic of the experimental setup and the relevant electronic levels of the ${\mathrm{Ca}}^{+}$ ion. The isotope shift of the 732-nm transition can be deduced from the isotope shifts of the 729-nm transition and of the D-fine-structure splitting. The D-fine-structure splitting is measured successively on the different calcium isotopes by direct frequency-comb Raman spectroscopy [18]. The transition frequency is deduced from the measurement of the comb’s repetition rate on a frequency counter referenced to a GPS-disciplined rubidium standard. The 729-nm laser used to probe the $4s{{}^2\mathrm{S}}_{1/2}\leftrightarrow 3d{{}^2\mathrm{D}}_{5/2}$ transition is frequency shifted by an AOM and is locked to an ultrastable high-finesse cavity providing a short-term linewidth $<1\mathrm{kHz}$. The absolute laser frequency is adjusted by a second AOM and deduced from a measurement on the frequency counter of the beating between the laser and the frequency comb. For both transition measurements, the frequency comb’s repetition rate is phase locked to a DDS referenced to the GPS-disciplined rubidium standard.