Three-dimensional Magneto-optical Trapping of Barium Monofluoride

TL;DR

This paper demonstrates the first three-dimensional magneto-optical trapping of BaF molecules, enabling cold molecules suitable for precision measurements of electric dipole moments.

Contribution

It introduces a method to trap BaF molecules using laser cooling with vibrational and rotational repumping, achieving effective closure of leakage channels.

Findings

Successfully trapped approximately 3,000 BaF molecules.

Achieved near-zero velocity deceleration of BaF molecules.

Enabled potential for ultracold BaF molecules for precision measurements.

Abstract

As a heavy molecule, barium monofluoride (BaF) presents itself as a promising candidate for measuring permanent electric dipole moment. The precision of such measurements can be significantly enhanced by utilizing a cold molecular sample. Here we report the realization of three-dimensional magneto-optical trapping (MOT) of BaF molecules. Through the repumping of all the vibrational states up to $v=3$, and rotational states up to $N=3$, we effectively close the transition to a leakage level lower than $10^{-5}$. This approach enables molecules to scatter a sufficient number of photons required for laser cooling and trapping. By employing a technique that involves chirping the slowing laser frequency, BaF molecules are decelerated to near-zero velocity, resulting in the capture of approximately $3\times 10^3$ molecules in a dual-frequency MOT setup. Our findings represent a significant step towards the realization of ultracold BaF molecules and the conduct of precision measurements with cold molecules.