Numerical modeling of laser cooling in molecules: From simple diatomics to polyatomics and radioactive species

Abstract

Optical Bloch equations and rate equations serve as powerful tools to model light-matter interactions from textbook-like two-level atoms to the complex internal dynamics of molecules. A particular challenge in this context is posed by molecular laser cooling, where many dozens or hundreds of levels need to be taken into account for a comprehensive modeling. Here, we present MoleCool, a numerically efficient Python toolbox to implement and solve the corresponding differential equation systems. We illustrate both the capabilities of the toolbox and some of the intricacies of molecular laser cooling by educational examples, which range from simple Rabi oscillations to spontaneous and coherent cooling schemes for various currently studied or considered molecular species. This includes, in particular, a comprehensive modeling of laser cooling dynamics with full hyperfine structure resolution in radioactive radium monofluoride (RaF), as well as studies of other complex species such as barium monofluoride (BaF) and ytterbium monohydroxide (YbOH). Program summary: Program title: MoleCool CPC Library link to program files: https://doi.org/10.17632/p682j3c3bh.1 Developer's repository link: https://github.com/LangenGroup/MoleCool Licensing provisions: MIT license Programming language: Python ≥ 3.8 Nature of problem: Modeling and calculating the forces arising in the laser cooling of complex molecules. Solution method: A Python package that solves the corresponding sets of differential equations.