# Efficient production of long-lived ultracold Sr$_2$ molecules

## TL;DR

This paper demonstrates an efficient method to produce long-lived ultracold Sr$_2$ molecules with over 80% efficiency by optimizing optical lattice parameters and STIRAP process, surpassing previous results.

## Contribution

The authors achieved a significant increase in molecule production efficiency and lifetime by improving optical lattice detuning and compensating light shifts during STIRAP.

## Key findings

- Molecular lifetime extended beyond one minute.
- Molecule association efficiency exceeded 80%.
- Insights into STIRAP limitations and optimization.

## Abstract

We associate Sr atom pairs on sites of a Mott insulator optically and coherently into weakly-bound ground-state molecules, achieving an efficiency above 80\%. This efficiency is 2.5 times higher than in our previous work [S. Stellmer, B. Pasquiou, R. Grimm, and F. Schreck, Phys. Rev. Lett. 109, 115302 (2012)] and obtained through two improvements. First, the lifetime of the molecules is increased beyond one minute by using an optical lattice wavelength that is further detuned from molecular transitions. Second, we compensate undesired dynamic light shifts that occur during the stimulated Raman adiabatic passage (STIRAP) used for molecule association. We also characterize and model STIRAP, providing insights into its limitations. Our work shows that significant molecule association efficiencies can be achieved even for atomic species or mixtures that lack Feshbach resonances suitable for magnetoassociation.