# Laser spectroscopy of hyperfine structure in highly-charged ions: a test of QED at high fields

## TL;DR

This paper discusses laser spectroscopy experiments on highly-charged ions to precisely measure hyperfine structures, enabling tests of quantum electrodynamics (QED) effects at high electromagnetic fields.

## Contribution

It introduces a new experimental approach using high-resolution laser spectroscopy on highly-charged ions to test QED effects at high fields with unprecedented precision.

## Key findings

- Hyperfine splitting measurements will be three orders of magnitude more precise.
- Comparison of hydrogen- and lithium-like ions allows QED effects to be determined within a few percent.
- Several candidate ions for laser spectroscopy studies are identified.

## Abstract

An overview is presented of laser spectroscopy experiments with cold, trapped, highly-charged ions, which will be performed at the HITRAP facility at GSI in Darmstadt (Germany). These high-resolution measurements of ground state hyperfine splittings will be three orders of magnitude more precise than previous measurements. Moreover, from a comparison of measurements of the hyperfine splittings in hydrogen- and lithium-like ions of the same isotope, QED effects at high electromagnetic fields can be determined within a few percent. Several candidate ions suited for these laser spectroscopy studies are presented.