Molecular Asymmetry and Optical Cycling: Laser Cooling Asymmetric Top Molecules

• Published in: Physical review. X Vol. 10; no. 3; p. 031022
• Main Authors: Augenbraun, Benjamin L., Doyle, John M., Zelevinsky, Tanya, Kozyryev, Ivan
• Format: Journal Article
• Language: English
• Published: College Park American Physical Society 01.07.2020; American Physical Society (APS)
• Subjects: Astrochemistry; Astronomy; Asymmetry; Atomic & molecular structure; ATOMIC AND MOLECULAR PHYSICS; Chemists; Cold and ultracold molecules; Complexity; Cooling; Cycles; Data processing; Diatomic molecules; Laser cooling; Lasers; Molecular structure; Molecule trapping & guiding; Molecules; Photon scatter; Photons; Physicists; Quantum phenomena; Standard model (particle physics); Symmetry
• ISSN: 2160-3308; 2160-3308
• DOI: 10.1103/PhysRevX.10.031022

We present a practical roadmap to achieve optical cycling and laser cooling of asymmetric top molecules (ATMs). Our theoretical analysis describes how reduced molecular symmetry, as compared to diatomic and symmetric nonlinear molecules, plays a role in photon scattering. We present methods to circumvent limitations on rapid photon cycling in these systems. We calculate vibrational branching ratios for a diverse set of asymmetric top molecules and find that many species within a broad class of molecules can be effectively cooled with a manageable number of lasers. We also describe methods to achieve rotationally closed optical cycles in ATMs. Despite significant structural complexity, laser cooling can be made effective by using extensions of the current techniques for linear molecules. Potential scientific impacts of laser-cooled ATMs span frontiers in controlled chemistry, quantum simulation, and searches for physics beyond the Standard Model.