Parity-Doublet Coherence Times in Optically Trapped Polyatomic Molecules

Polyatomic molecules provide complex internal structures that are powerful tools for applications in quantum information science, quantum simulation, and precision searches for physics beyond the Standard Model. One key feature of polyatomic molecules is the presence of parity-doublet states. These structures generically arise from the rotational and vibrational degrees of freedom afforded by polyatomic molecules. Linear triatomic molecules contain ℓ-type parity-doublet states in the vibrational bending mode, and are predicted to exhibit robust coherence properties. Here we report optically trapped CaOH molecules prepared in ℓ-type parity-doublet states in the (010) bending mode and realize a bare qubit coherence time of T2* = 0.8(2) s, which is longer than the 0.36 s lifetime of the bending mode. Using molecular spectroscopy to probe the molecular environment, we suppress differential Stark shifts by canceling ambient electric fields. We characterize the parity-dependent trap shifts that are found to limit the coherence time. The parity-doublet coherence times achieved in this work motivate future efforts exploring spin-exchange interactions in optical tweezer arrays and laser cooling of asymmetric top molecules, which contain parity-doublet states in the vibrational ground state.