Testing inter-electronic interaction in lithium-like tin

TL;DR

This paper reports a highly precise measurement of the g-factor of lithium-like tin and compares it with advanced theoretical calculations, providing a stringent test of quantum electrodynamics at high nuclear charge.

Contribution

It presents the first high-precision g-factor measurement for lithium-like tin and refines theoretical predictions by incorporating experimental data to account for higher-order QED effects.

Findings

Measured g-factor of lithium-like tin with 0.5 ppb accuracy

Confirmed the revised QED theory at high nuclear charge Z=50

Improved understanding of inter-electronic interactions in heavy ions

Abstract

Magnetic moments of bound-electron systems are a sensitive tool for testing fundamental interactions. $g$ factors of lithium-like ions have been rigorously studied in recent years, enabling insights into the relativistic inter-electronic effects. Here, we present the $g$-factor measurement of lithium-like tin, accurate to 0.5 parts per billion, as well as \textit{ab initio} theoretical calculations that include an advanced treatment of the inter-electronic interaction. We further improve the prediction by using the experimental result for the hydrogen-like tin $g$ factor, inferring from it the unknown higher-order QED effects. The observed agreement independently confirms the revised theory at a previously inaccessible high nuclear charge $Z$ of 50, where QED effects are significantly larger.