Precision probing of ionic-core transitions in alkaline-earth Rydberg atoms

TL;DR

This paper presents high-resolution spectroscopy of ionic-core transitions in alkaline-earth Rydberg atoms, achieving unprecedented spectral precision through dynamical control and direct comparison with a trapped ion reference.

Contribution

It introduces a method for reducing linewidths in ionic-core transition measurements and demonstrates precise isotope and hyperfine splitting measurements in Rydberg atoms.

Findings

Linewidth reduced by over two orders of magnitude

First high-resolution measurements of isotope shifts and hyperfine splitting in ionic cores

Direct comparison with a trapped ion enhances spectral accuracy

Abstract

We report precision spectroscopy of ionic-core transitions in alkaline-earth Rydberg atoms. We demonstrate high-resolution measurements of isotope shifts and hyperfine splitting of dipole transitions in ionic cores which have not been explored so far. A key element of this work is the reduction of the linewidth by more than two orders of magnitude enabled by dynamical control of Rydberg electron's orbit which significantly enhances the spectral resolution. Furthermore, to unambiguously identify the frequency shift, we directly compare core ion's spectrum with a signal from a single trapped ion serving as an ultimate frequency reference. This work provides an important foundation for quantum control of inner-core transitions, which offer an useful tool in manipulating Rydberg atom as well as a sensitive probe for electron-core interactions in atomic and molecular systems.