Measuring Fundamental Symmetry Violation in Polyatomic Molecules

Citation

Jadbabaie, Arian (2023) Measuring Fundamental Symmetry Violation in Polyatomic Molecules. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/2jry-1s28. https://resolver.caltech.edu/CaltechTHESIS:06022023-203550284

Abstract

Open questions in fundamental physics, such as the cosmological origins of the observed imbalance of matter and antimatter, motivate the search for fundamental symmetry violating physics beyond the Standard Model (BSM). Recent measurements of heavy, polar, diatomic molecules constrain the existence of new, Parity (P) and Time-reversal (T) violating physics at 10-50 TeV energy scales, exceeding the reach of particle colliders. The power of existing molecular measurements motivates us to pursue the next-generation of searches for symmetry violation. By adopting polyatomic molecules as an experimental platform, we can generically combine laser-cooling and trapping, BSM sensitivity, and exquisite quantum control over P and/or T violating energy shifts. These improvements are projected to increase the sensitivity of measurements to the PeV energy scale. In this thesis, we develop the foundations for new physics searches using cold and ultracold, linear triatomic molecules. These molecules have long-lived vibrational bending modes with closely spaced, opposite parity doublets, a key structure that aids polarizability, molecule control, state engineering, and systematic suppression. We produce a cryogenic buffer gas beam of cold YbOH molecules, using laser-enhanced chemical reactions to increase molecular yield by an order of magnitude. As a prerequisite for precision measurements, we perform high-resolution spectroscopic characterization of both the ground and excited bending modes of YbOH. Next, we present detailed tests of quantum state preparation and readout protocols in a YbOH beam, successfully demonstrating Ramsey interferometry using two-photon transitions. Finally, as part of the PolyEDM collaboration, we illustrate the power of polyatomic molecules by combining laser cooling and optical trapping with quantum state engineering to perform proof-of-principle measurements of P,T violating physics in magnetically-insensitive states of ultracold CaOH molecules at Harvard University. Our results open the door to a wide range of quantum-enhanced symmetry violation searches benefiting from the unique structural features of polyatomic molecules.

Thesis Files