Optimized production of ultracold ground-state molecules: Stabilization employing potentials with ion-pair character and strong spin-orbit coupling

TL;DR

This paper explores a method to produce ultracold ground-state molecules efficiently by using tailored laser pulses and optimal control theory to enhance population transfer in photoassociation processes involving ion-pair states.

Contribution

It introduces a novel approach combining ion-pair character and strong spin-orbit coupling with optimal control to significantly improve molecule stabilization efficiency.

Findings

Chirped and shaped laser pulses increase stabilization efficiency by up to two orders of magnitude.

Optimal control theory identifies the most effective pathways for population transfer.

Ion-pair states with strong spin-orbit interaction are effective for ultracold molecule production.

Abstract

We discuss the production of ultracold molecules in their electronic ground state by photoassociation employing electronically excited states with ion-pair character and strong spin-orbit interaction. A short photoassociation laser pulse drives a non-resonant three-photon transition for alkali atoms colliding in their lowest triplet state. The excited state wave packet is transferred to the ground electronic state by a second laser pulse, driving a resonant two-photon transition. After analyzing the transition matrix elements governing the stabilization step, we discuss the efficiency of population transfer using transform-limited and linearly chirped laser pulses. Finally, we employ optimal control theory to find the most efficient stabilization pathways. We find that the stabilization efficiency can be increased by one and two orders of magnitude for linearly chirped and optimally shaped laser pulses, respectively.