Search for ultralight dark matter from long-term frequency comparisons of optical and microwave atomic clocks

TL;DR

This study uses long-term frequency comparisons between optical and microwave atomic clocks to search for ultralight scalar dark matter, setting new limits on its couplings and contributing to SI second redefinition.

Contribution

It provides new experimental limits on ultralight dark matter couplings using 298 days of clock data and refines the absolute frequency of the Yb clock transition.

Findings

Set new limits on scalar dark matter-electron and gluon couplings.

Determined the absolute frequency of the Yb clock transition.

Contributed to SI second redefinition efforts.

Abstract

We search for ultralight scalar dark matter candidates that induce oscillations of the fine structure constant, the electron and quark masses, and the quantum chromodynamics energy scale with frequency comparison data between an $^{171}$Yb optical lattice clock and a $^{133}$Cs fountain microwave clock that span 298 days with an uptime of 15.4 $\%$. New limits on the couplings of the scalar dark matter to electrons and gluons in the mass range from $10^{-22}$ eV/$c^{2}$ to $10^{-20}$ eV/$c^{2}$ are set, assuming that each of these couplings is the dominant source of the modulation in the frequency ratio. The absolute frequency of the $^{171}$Yb clock transition is also determined as $518\,295\,836\,590\,863.69(28)$ Hz, which is one of the important contributions towards a redefinition of the SI second.