Creation and precise spectroscopy of $^{86}$Sr$_2$ halo molecules

TL;DR

This paper reports the creation and precise spectroscopic measurement of $^{86}$Sr$_2$ halo molecules, enabling future isotope shift studies and advancing understanding of weakly bound molecular states in strontium.

Contribution

It demonstrates efficient production and detailed spectroscopy of $^{86}$Sr$_2$ halo molecules, providing accurate vibrational energy measurements and systematic uncertainty analysis.

Findings

Vibrational splittings measured with sub-100 Hz uncertainty

Identification of optimal pathways for molecule production

Absolute binding energies determined for weakly bound states

Abstract

We report on the creation of $^{86}$Sr$_2$ molecules in the halo state and neighboring weakly bound states. Efficient molecule production via one-photon photoassociation relies on sufficient wavefunction overlap between the target vibrational states in the electronic excited- and ground-state potentials. Using Autler-Townes spectroscopy, transition strengths are measured to identify optimal pathways for production of weakly bound molecules. Vibrational splittings for the three least-bound vibrational states are measured, and dominant systematic uncertainties are evaluated with uncertainties below 100 Hz. From these splittings, absolute binding energies for these weakly bound vibrational states are determined. The results pave the way to a molecular isotope shift measurement with Sr$_2$.