Speaker
Description
It has been more than a decade since highly charged ions (HCI) were first proposed as exciting candidates for next-generation frequency standards [1] and for precision tests of fundamental physics [2]. The technical obstacles hindering the development of a competitive clock based on a cold HCI have fallen one by one, starting with the extraction of an HCI from a hot plasma and sympathetic cooling using Be+ ions in a linear Paul trap [3], followed by quantum logic spectroscopy of the clock transition in a single HCI [4], and finally full control over the motional state of the HCI at the single-quantum level [5].
We will present preliminary results from the first measurement of the absolute frequency of an optical transition in an HCI using optical-clock-like spectroscopic techniques, obtained by local comparison to an optical frequency standard based on the electric octupole transition in 171Yb+ [6] using a femtosecond optical frequency comb. The measurement accuracy is almost eight orders of magnitude beyond the previous state of the art [7]. The main systematic perturbations of the clock transition are also evaluated, along with measurements of some important atomic properties such as the g-factor and quadrupole moment of the excited electronic state. These results bring HCI finally into the accuracy realm of optical atomic clocks.
[1] S.Schiller, “Hydrogenlike Highly Charged Ions for Tests of the Time Independence of Fundamental Constants”, Phys. Rev. Lett. 98, 180801 (2007)
[2] J.Berengut, V. Dzuba, and V. Flambaum, “Enhanced Laboratory Sensitivity to Variation of the Fine-Structure Constant using Highly Charged Ions”, Phys. Rev. Lett. 105, 120801 (2010)
[3] L.Schmöger et al., “Coulomb crystallization of highly charged ions”, Science 347, pp. 1233-1236 (2015)
[4] P. Micke et al., “Coherent laser spectroscopy of highly charged ions using quantum logic”, Nature 578, pp. 60-65 (2020)
[5] S. A. King et al., “Algorithmic Ground-state Cooling of Weakly-Coupled Oscillators using Quantum Logic”, Phys. Rev. X (accepted), arXiv:2102.12427v2 (2021)
[6] N. Huntemann et al., “Single-Ion Atomic Clock with 3×10^−18 Systematic Uncertainty”, Phys. Rev. Lett. 116, 063001 (2016)
[7] A. Egl et al., “Application of the Continuous Stern-Gerlach Effect for Laser Spectroscopy of the 40Ar13+ Fine Structure in a Penning Trap”, Phys. Rev. Lett. 123, 123001 (2019)
