Trap-induced ac Zeeman shift of the thorium-229 nuclear clock frequency
We identify a significant threat to the accuracy of the highly anticipated nuclear clock based on $^229}$Th$^3+}$ [C. J. Campbell \it et al.}, Phys.\ Rev.\ Lett.\ 108, 120802 (2012)]. In particular, we demonstrate that the clock is susceptible to parasitic rf magnetic fields associated with the ion trapping. For typical field strengths ($\sim\!\mu$T), the ac Zeeman shift to the clock frequency may exceed the projected systematic uncertainty of the clock by orders of magnitude. By developing a theoretical treatment that incorporates the effects of a dc magnetic field, we propose a means to suppress this problematic shift. Specifically, we show that the ac Zeeman shifts to the clock levels cancel to a high degree when operating with a large dc magnetic field, restoring prospects for unprecedented clock accuracy.
Trap-induced ac Zeeman shift of the thorium-229 nuclear clock frequency, Physical Review Letters, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=934770
(Accessed June 2, 2023)