Deflection of barium monofluoride molecules using the bichromatic force: A density-matrix simulation

TL;DR

This study uses detailed density-matrix simulations to demonstrate that bichromatic laser forces can effectively deflect and separate BaF molecules from other products, aiding precision measurements of the electron's electric dipole moment.

Contribution

It provides a comprehensive simulation approach for optical deflection of BaF molecules using bichromatic forces, including Doppler and phase effects, which was not previously detailed.

Findings

Bichromatic force can sufficiently deflect BaF molecules for separation.

Simulation accounts for Doppler shift, intensity, and phase evolution during molecule transit.

Results compare favorably with previous π-pulse deflection schemes.

Abstract

A full density-matrix simulation is performed for optical deflection of a barium monofluoride ($^{138}$Ba$^{19}$F) beam using the bichromatic force, which employs pairs of counter-propagating laser beams that are offset in frequency. We show that the force is sufficient to separate BaF molecules from the other products generated in a helium-buffer-gas-cooled ablation source. For our simulations, the density-matrix and force equations are numerically integrated during the entire time that the molecules pass through a laser beam to ensure that effects of the evolution of the Doppler shift and of the optical intensity and phase at the position of the molecule are properly included. The results of this work are compared to those of a deflection scheme (Phys. Rev. A 107, 032811 (2023)) which uses $\pi$ pulses to drive frequency-resolved transitions. This work is part of an effort by the EDM$^3$ collaboration to measure the electric dipole moment of the electron using BaF molecules embedded in a cryogenic argon solid. Separation of BaF molecules will aid in producing a sufficiently pure solid.