Bose-Einstein condensation of alkaline earth atoms: $^{40}${Ca}

TL;DR

This paper reports the first achievement of Bose-Einstein condensation in an alkaline earth atom, specifically $^{40}$Ca, enabling new research avenues in precision measurement and molecular physics.

Contribution

The paper demonstrates Bose-Einstein condensation of $^{40}$Ca and develops an optimized cooling scheme for alkaline earth atoms, a novel achievement in the field.

Findings

Achieved Bose-Einstein condensation of $^{40}$Ca with about 20,000 atoms.

Measured elastic and inelastic collision effects related to the large scattering length.

Developed a rapid, efficient cooling and condensation process within 3 seconds.

Abstract

We have achieved Bose-Einstein condensation of $^{40}$Ca, the first for an alkaline earth element. The influence of elastic and inelastic collisions associated with the large ground state s-wave scattering length of $^{40}$Ca was measured. From these findings, an optimized loading and cooling scheme was developed that allowed us to condense about $2 \cdot 10^4$ atoms after laser cooling in a two-stage magneto-optical trap and subsequent forced evaporation in a crossed dipole trap within less than 3 s. The condensation of an alkaline earth element opens novel opportunities for precision measurements on the narrow intercombination lines as well as investigations of molecular states at the $^1$S--$^3$P asymptotes.