High-resolution spectroscopy of ionic-core transitions in alkaline-earth-metal Rydberg atoms
Phys. Rev. A 114, 042803 – Published 6 October, 2026
DOI: https://doi.org/10.1103/2pt2-5p1p
Abstract
We report high-resolution spectroscopy of ionic-core transitions in alkaline-earth-metal Rydberg atoms. We perform high-resolution measurements of isotope shifts and the hyperfine splitting of dipole transitions in the ionic core. A key element of this work is the reduction of the linewidth by more than two orders of magnitude, enabled by the dynamical control of the Rydberg electron's orbit, which significantly enhances the spectral resolution. Furthermore, to unambiguously identify the frequency shift, we directly compare the core ion's spectrum with a signal from a single trapped ion serving as a frequency reference, which represents a completely isolated system.
