Developing a field independent frequency reference by averaging over transitions to multiple hyperfine levels

TL;DR

This paper introduces a method to create a magnetic and electric field independent frequency reference by averaging over hyperfine transitions, effectively canceling shifts caused by external fields, demonstrated with Lu+ ions.

Contribution

The paper presents a novel averaging technique over hyperfine transitions to cancel quadrupole and Zeeman shifts, applicable to various atomic species for stable frequency references.

Findings

Quadrupole and Zeeman shifts are canceled by averaging over hyperfine transitions.

The method is demonstrated with Lu+ ions.

Applicable to other atomic species for improved clock stability.

Abstract

We show that by averaging over transitions to multiple hyperfine levels, quadrupole shifts and dominant Zeeman effects exactly cancel whenever the nuclear spin, I, is at least as large as the total electronic angular momentum, J. The average frequency thus defines a frequency reference which is inherently independent of external magnetic fields and electric field gradients. We use Lu+ to illustrate the method although the approach could be readily adapted to other atomic species. This approach practically eliminates the quadrupole and Zeeman shift considerations for many clock candidates.