Precision frequency measurements with entangled states

TL;DR

This paper demonstrates how entangled states of trapped ions can be used to improve the precision of frequency measurements by suppressing systematic shifts and accurately measuring small external field shifts, advancing ion clock technology.

Contribution

It introduces a method using maximally entangled ion states to suppress Zeeman shifts and measure electric quadrupole shifts without relying on field-independent transitions.

Findings

Suppressed linear Zeeman shifts using entangled states.

Achieved accurate measurement of electric quadrupole shifts.

Enhanced precision in ion clock frequency measurements.

Abstract

We demonstrate how quantum entanglement can be used for precision frequency measurements with trapped ions. In particular, we show how to suppress linear Zeeman shifts in optical frequency measurements by using maximally entangled states of two ions even if the individual ions do not have any field-independent transition. In addition, this technique allows for an accurate measurement of small external field frequency shifts such as the electric quadrupole shift which are important for ion clock experiments.