Two clock transitions in neutral Yb for the highest sensitivity to variations of the fine-structure constant

TL;DR

This paper proposes a new neutral Yb-based optical clock transition with exceptional sensitivity to variations in the fine-structure constant, enabling advanced tests of fundamental physics and dark matter detection.

Contribution

It introduces a novel Yb transition with the highest known sensitivity to alpha variation, enhancing the potential for fundamental physics experiments.

Findings

Alpha-variation enhancement factor of -15 for the new transition.

18 times larger sensitivity compared to other neutral atomic clocks.

Potential for improved tests of fundamental constants and dark matter searches.

Abstract

We propose a new frequency standard based on a $4f^{14} 6s6p~ ^3\!P_0 - 4f^{13} 6s^2 5d ~(J=2)$ transition in neutral Yb. This transition has a potential for high stability and accuracy and the advantage of the highest sensitivity among atomic clocks to variation of the fine-structure constant $\alpha$. We find its dimensionless $\alpha$-variation enhancement factor to be $K=-15$, in comparison to the most sensitive current clock (Yb$^+$ E3, $K=-6$), and it is 18 times larger than in any neutral-atomic clocks (Hg, $K=0.8$). Combined with the unprecedented stability of an optical lattice clock for neutral atoms, this high sensitivity opens new perspectives for searches for ultralight dark matter and for tests of theories beyond the standard model of elementary particles. Moreover, together with the well-established $^1\!S_0 -\, ^3\!P_0$ transition one will have two clock transitions operating in neutral Yb, whose interleaved interrogations may further reduce systematic uncertainties of such clock-comparison experiments.