Frequency metrology on the 4s 2S1/2 - 4p 2P1/2 transition in the calcium ion for a comparison with quasar data

TL;DR

This paper reports high-precision frequency measurements of a calcium ion transition using laser cooling and frequency comb calibration, aiming to compare with quasar data to investigate potential variations in the fine structure constant over cosmological times.

Contribution

It introduces a highly accurate frequency measurement of the calcium ion transition, significantly improving precision for cosmological constant variation studies.

Findings

Transition frequency measured as 755222766.2(1.7) MHz

Measurement accuracy improved by over an order of magnitude

Facilitates comparison with quasar data for fundamental constant variation

Abstract

High accuracy frequency metrology on the 4s 2S1/2 - 4p 2P1/2 transition in calcium ions is performed using laser cooled and crystallized ions in a linear Paul trap. Calibration is performed with a frequency comb laser, resulting in a transition frequency of f=755222766.2(1.7) MHz. The accuracy presents an improvement of more than one order of magnitude, and will facilitate a comparison with quasar data in a search for a possible change of the fine structure constant on a cosmological time scale.