Evaluation of trap-induced systematic frequency shifts for a multi-ion optical clock at the $10^{-19}$ level

TL;DR

This paper reports on reducing trap-induced frequency shifts in a multi-ion optical clock, achieving uncertainties below 10^{-19} by controlling micromotion, secular motion heating, and black-body radiation effects.

Contribution

It introduces scalable segmented Paul traps and demonstrates methods to minimize key systematic frequency shifts in multi-ion optical clocks.

Findings

Fractional frequency uncertainty below 10^{-19} for key effects

Effective reduction of Doppler and heating shifts

Black-body radiation shift minimized

Abstract

In order to improve the short-term stability of trapped-ion optical clocks, we are developing a frequency standard based on ${}^{115}$In${}^+$ / ${}^{172}$Yb${}^+$ Coulomb crystals. For this purpose, we have developed scalable segmented Paul traps which allow a high level of control for multiple ion ensembles. In this article, we detail on our recent results regarding the reduction of the leading sources of frequency uncertainty introduced by the ion trap: 2nd-order Doppler shifts due to micromotion and the heating of secular motion, as well as the black-body radiation shift due to warming of the trap. We show that the fractional frequency uncertainty due to each of these effects can be reduced to well below $10^{-19}$.