Creation of ultracold Sr2 molecules in the electronic ground state

TL;DR

This paper demonstrates the creation of ultracold Sr2 molecules in the electronic ground state using STIRAP, achieving high efficiency and full quantum control, advancing molecular quantum state engineering.

Contribution

It introduces a novel STIRAP-based method for forming ultracold molecules without Feshbach resonances, applicable to a broad range of systems.

Findings

Achieved 30% transfer efficiency in molecule formation.

Produced 4x10^4 ultracold Sr2 molecules with full quantum state control.

Determined binding energies of key vibrational levels.

Abstract

We report on the creation of ultracold 84Sr2 molecules in the electronic ground state. The molecules are formed from atom pairs on sites of an optical lattice using stimulated Raman adiabatic passage (STIRAP). We achieve a transfer efficiency of 30% and obtain 4x10^4 molecules with full control over the external and internal quantum state. STIRAP is performed near the narrow 1S0-3P1 intercombination transition, using a vibrational level of the 0u potential as intermediate state. In preparation of our molecule association scheme, we have determined the binding energies of the last vibrational levels of the 0u, 1u excited-state, and the 1\Sigma_g^+ ground-state potentials. Our work overcomes the previous limitation of STIRAP schemes to systems with Feshbach resonances, thereby establishing a route that is applicable to many systems beyond bi-alkalis.