Ion optical clocks with three electronic states

TL;DR

This paper proposes a simplified and robust optical clock design using trapped alkali-like ions with three electronic states, reducing laser complexity and enabling transportability.

Contribution

It introduces a novel ion optical clock concept with fewer laser requirements and hyperfine techniques, focusing on $^{225}$Ra$^{+}$ for improved robustness and portability.

Findings

Reduced laser wavelength requirements compared to traditional clocks

Use of hyperfine state techniques enabled by nuclear spin

Potential for transportable optical clock development

Abstract

Optical clocks are the apotheosis of precision measurement, but they require frequent maintenance by scientists. The supporting laser systems are a particularly demanding component of these instruments. To reduce complexity and increase robustness we propose an optical clock with trapped alkali-like ions that use the $S_{1/2}\rightarrow D_{3/2}$ electric quadrupole transition. Compared to traditional group-II ion clocks this reduces the number of laser wavelengths required, and uses hyperfine state preparation and readout techniques enabled by the nuclear spin $I=1/2$. We consider $^{225}$Ra$^{+}$ as a candidate system for a clock with three electronic states, and discuss the potential to help realize a transportable optical clock.