Characterizing the fundamental bending vibration of a linear polyatomic molecule for symmetry violation searches

Abstract

Polyatomic molecules have been identified as sensitive probes of charge-parity violating and parity violating physics beyond the Standard Model (BSM). For example, many linear triatomic molecules are both laser-coolable and have parity doublets in the ground electronic X 2Σ+(010) state arising from the bending vibration, both features that can greatly aid BSM searches. Understanding the X 2Σ+(010) state is a crucial prerequisite to precision measurements with linear polyatomic molecules. Here, we characterize the fundamental bending vibration of 174YbOH using high-resolution optical spectroscopy on the nominally forbidden X 2Σ+(010) → Α 2Π1/2(000) transition at 588 nm. We assign 39 transitions originating from the lowest rotational levels of the X 2Σ+(010) state, and accurately model the state's structure with an effective Hamiltonian using best-fit parameters. Additionally, we perform Stark and Zeeman spectroscopy on the X 2Σ+(010) state and fit the molecule-frame dipole moment to D mol = 2.16(1) D and the effective electron g-factor to gS = 2.07(2). Further, we use an empirical model to explain observed anomalous line intensities in terms of interference from spin-orbit and vibronic perturbations in the excited Α 2Π1/2(000) state. Our work is an essential step toward searches for BSM physics in YbOH and other linear polyatomic molecules.

Quantum control of trapped polyatomic molecules for eEDM searches

“…Following this roadmap with heavier trapped polyatomic molecules has the potential to provide orders-of-magnitude improvements to present bounds on T-violating physics. Using a recent study of the X˜010 state in YbOH ( 37 ), we identified similar N = 1 zero g -factor states for eEDM measurements with greatly improved sensitivity. In addition to the g -factor tuning demonstrated in this work, polyatomic molecules provide the ability to reverse the sign of Σ without reversing M S , which is a crucial feature of recent experiments that has greatly improved the limit on the eEDM ( 25 , 27 ).…”