Two-step Doppler cooling of a three-level ladder system with an intermediate metastable level

TL;DR

This paper analyzes two-step Doppler cooling in a three-level ladder system with a metastable intermediate state, providing analytical and numerical results relevant to recent atomic cooling experiments.

Contribution

It introduces a detailed analysis of Doppler cooling in a three-level ladder system with a metastable intermediate level, including comparisons to two-level cooling methods.

Findings

Analytical and numerical results for scattering rates and temperatures.

Comparison with two-level Doppler cooling techniques.

Relevance to experiments on alkali-earth atoms and ions.

Abstract

Doppler laser cooling of a three-level ladder system using two near-resonant laser fields is analyzed in the case of the intermediate level being metastable while the upper level is short-lived. Analytical as well as numerical results for e.g. obtainable scattering rates and achievable temperatures are presented. When appropriate, comparisons with two-level single photon Doppler laser cooling is made. These results are relevant to recent experimental Doppler laser cooling investigations addressing intercombination lines in alkali-earth metal atoms and quadrupole transitions in alkali-earth metal ions.