Nuclear deformation as a source of the non-linearity of King plot in the Yb$^+$ ion

TL;DR

This study shows that nuclear deformation significantly contributes to the non-linearity observed in the King plot for Yb$^+$ ions, aligning theoretical predictions with experimental data.

Contribution

It provides the first comprehensive atomic and nuclear calculations linking nuclear deformation to King plot non-linearity in Yb$^+$ ions.

Findings

Nuclear deformation explains the observed King plot non-linearity.

Calculated nuclear parameters match experimental isotope shifts.

Nuclear models predict strong quadrupole deformation consistent with data.

Abstract

We perform atomic relativistic many-body calculations of the field isotope shifts and calculations of corresponding nuclear parameters for all stable even-even isotopes of Yb$^+$ ion. We demonstrate that if we take nuclear parameters of the Yb isotopes from a range of the state-the-art nuclear models which all predict strong quadrupole nuclear deformation, then calculated non-linearity of the King plot, caused by the difference in the deformation in different isotopes, is consistent with the non-linearity observed in the experiment (Ian Counts {\em et al}, Phys. Rev. Lett. {\bf 125}, 123002 (2020)). The changes of nuclear RMS radius between isotopes extracted from experiment are consistent with those obtained in the nuclear calculations.