A high-precision rf trap with minimized micromotion for an In+ multiple-ion clock

TL;DR

This paper reports the development and characterization of a high-precision linear ion trap optimized for a multi-ion optical clock using In+ ions, with minimized micromotion to improve clock accuracy.

Contribution

The paper introduces a novel trap design based on FEM calculations, details its manufacturing, and demonstrates micromotion measurement with high sensitivity for optical clock applications.

Findings

Micromotion amplitude resolution of 1.1 nm achieved

Residual axial rf fields measured and compared to FEM predictions

Estimated capacity of 12 ions per segment with fractional inaccuracy ≤ 1×10^-18

Abstract

We present an experiment to characterize our new linear ion trap designed for the operation of a many-ion optical clock using 115-In^+ as clock ions. For the characterization of the trap as well as the sympathetic cooling of the clock ions we use 172-Yb^+. The trap design has been derived from finite element method (FEM) calculations and a first prototype based on glass-reinforced thermoset laminates was built. This paper details on the trap manufacturing process and micromotion measurement. Excess micromotion is measured using photon-correlation spectroscopy with a resolution of 1.1nm in motional amplitude, and residual axial rf fields in this trap are compared to FEM calculations. With this method, we demonstrate a sensitivity to systematic clock shifts due to excess micromotion of |({\Delta}{\nu}/{\nu})| = 8.5x10^-20. Based on the measurement of axial rf fields of our trap, we estimate a number of twelve ions that can be stored per trapping segment and used as an optical frequency standard with a fractional inaccuracy of \leq 1x10^-18 due to micromotion.