Highly charged Nd${}^{9+}$ Ion: A potential candidate of $\upmu$Hz linewidth optical clocks for probing fundamental physics

Yan-mei Yu, Duo Pan, Shaolong Chen +3

An active optical clock based on highly charged Nd${}^{9+}$ ion is proposed for the first time. The clock can offer ultra-narrow linewidth at the $\upmu$Hz-level which is more than t…