Hf$^{12+}$ ion: Highly Charged Ion for Next-Generation Atomic Clocks and Tests of Fundamental Physics

TL;DR

This study computationally investigates the Hf$^{12+}$ ion's electronic structure, demonstrating its potential for highly accurate atomic clocks and fundamental physics tests due to its low perturbation sensitivities and high sensitivity to variations in the fine-structure constant.

Contribution

The paper introduces advanced computational analysis of Hf$^{12+}$, highlighting its suitability for next-generation atomic clocks and fundamental physics experiments, with specific focus on its unique transition properties.

Findings

Hf$^{12+}$ has two clock transitions with high sensitivity to $eta$ variations.

The ion exhibits very small blackbody-radiation shifts, ideal for precision measurements.

The quadrupole shift can be minimized, enhancing clock stability.

Abstract

We use advanced computational techniques to study the electronic structure of the Hf$^{12+}$ ion, with the goal of assessing its potential for use in highly accurate atomic optical clocks and search for new physics. Such clocks should combine low sensitivity to external perturbations with high sensitivity to a possible time variation of the fine-structure constant $\alpha$. The system features two clock transitions. One is an $f-p$ transition in terms of single-electron states, which exhibits strong sensitivity to variations in $\alpha$. The other is an electric-quadrupole (E2) transition between states of the ground-state configuration, which can serve as an anchor transition for measuring one frequency against the other. All three relevant states possess very small and nearly equal static dipole polarizabilities, resulting in an extremely small blackbody-radiation shift. The quadrupole shift is also small and can be further suppressed. Altogether, Hf$^{12+}$ appears to be a highly promising candidate for both precision timekeeping and searches for new physics.