Magneto optical trapping of Barium

TL;DR

This paper reports the first successful laser cooling and magneto-optical trapping of barium, demonstrating a new method to cool heavy alkaline earth elements with potential for broad applications.

Contribution

It introduces a novel laser cooling and trapping technique for barium, overcoming challenges posed by its complex energy level structure.

Findings

Achieved magneto-optical trapping of barium atoms.

Observed trapping lifetimes exceeding 1.5 seconds.

Demonstrated the feasibility of cooling heavy alkaline earth elements.

Abstract

First laser cooling and trapping of the heavy alkaline earth element barium has been achieved based on the strong 6s$^2$ $^1$S$_0$ - 6s6p $^1$P$_1$ transition for the main cooling. Due to the large branching into metastable D-states several additional laser driven transitions are required to provide a closed cooling cycle. A total efficiency of $0.4(1) \cdot 10^{-2}$ for slowing a thermal atomic beam and capturing atoms into a magneto optical trap was obtained. Trapping lifetimes of more than 1.5 s were observed. This lifetime is shortened at high laser intensities by photo ionization losses. The developed techniques will allow to extend significantly the number of elements that can be optically cooled and trapped.