In this chapter, we discuss the development of state preparation and readout schemes for precision measurements on linear polyatomic molecules. We begin with an introduction of relevant concepts for precision measurements with molecules, overviewing Rabi and Ramsey interferometry in Sect. 5.1. We then briefly review the schemes used by existing molecule experiments, namely ACME (ACME Collaboration, Nature:562(7727), 355–360, 2018) and JILA (Roussy et al., A new bound on the electron’s electric dipole moment, 2022), to perform state preparation and readout. In Sect. 5.5 we move on to describing initial state preparation tests in YbOH using coherent population trapping (CPT). We discuss difficulties with CPT that arise when working with species with unresolved hyperfine structure in the ground and excited states, and demonstrate a method for circumventing this issue by using circularly polarized light to perform spin precession in the \(\tilde {X}(000)\) ground state of YbOH. Then, in Sect. 5.6, we present state preparation and readout tests performed on the \(\tilde {X}(010)\) state in YbOH. For these tests, we use two-photon resonances, which encompass both resonant CPT and detuned Raman transitions. We demonstrate the power of two-photon transitions by performing hyperfine resolved spectroscopy on the \(N=1\) manifold of the \(\tilde {X}(010)\) state. Finally, we conclude by using two-photon transitions to perform Ramsey interferometry in the \(\tilde {X}(010)\) state in the presence of a magnetic field. The results of this section can be immediately generalized to precision measurements of \(P,T\) violating physics in YbOH. Finally, in Sect. 5.7, we present prototype electron EDM (eEDM) sensitive measurements in optically trapped CaOH. For these results, we collaborate with the Doyle group at Harvard. Trapped polyatomic molecules are particularly promising avenue for next-generation searches for \(P,T\) violation. We prepare ultracold CaOH molecules in a single quantum state, polarize them in an electric field, and use microwaves to perform Ramsey interferometry in an eEDM sensitive state. To extend the coherence time of the measurement, we utilize eEDM sensitive states with tunable, near-zero magnetic field sensitivity. Such “zero g-factor” states are generic in polyatomic molecules with parity doubling. Our results demonstrate the power of quantum state engineering for EDM searches, and provide a clear pathway towards orders-of-magnitude improved experimental sensitivity to \(P,T\) violating physics.

State Preparation and Measurement

章节
发表日期：

2025年

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Arian Jadbabaie

摘要

In this chapter, we discuss the development of state preparation and readout schemes for precision measurements on linear polyatomic molecules. We begin with an introduction of relevant concepts for precision measurements with molecules, overviewing Rabi and Ramsey interferometry in Sect. 5.1. We then briefly review the schemes used by existing molecule experiments, namely ACME (ACME Collaboration, Nature:562(7727), 355–360, 2018) and JILA (Roussy et al., A new bound on the electron’s electric dipole moment, 2022), to perform state preparation and readout. In Sect. 5.5 we move on to describing initial state preparation tests in YbOH using coherent population trapping (CPT). We discuss difficulties with CPT that arise when working with species with unresolved hyperfine structure in the ground and excited states, and demonstrate a method for circumventing this issue by using circularly polarized light to perform spin precession in the \(\tilde {X}(000)\) ground state of YbOH. Then, in Sect. 5.6, we present state preparation and readout tests performed on the \(\tilde {X}(010)\) state in YbOH. For these tests, we use two-photon resonances, which encompass both resonant CPT and detuned Raman transitions. We demonstrate the power of two-photon transitions by performing hyperfine resolved spectroscopy on the \(N=1\) manifold of the \(\tilde {X}(010)\) state. Finally, we conclude by using two-photon transitions to perform Ramsey interferometry in the \(\tilde {X}(010)\) state in the presence of a magnetic field. The results of this section can be immediately generalized to precision measurements of \(P,T\) violating physics in YbOH. Finally, in Sect. 5.7, we present prototype electron EDM (eEDM) sensitive measurements in optically trapped CaOH. For these results, we collaborate with the Doyle group at Harvard. Trapped polyatomic molecules are particularly promising avenue for next-generation searches for \(P,T\) violation. We prepare ultracold CaOH molecules in a single quantum state, polarize them in an electric field, and use microwaves to perform Ramsey interferometry in an eEDM sensitive state. To extend the coherence time of the measurement, we utilize eEDM sensitive states with tunable, near-zero magnetic field sensitivity. Such “zero g-factor” states are generic in polyatomic molecules with parity doubling. Our results demonstrate the power of quantum state engineering for EDM searches, and provide a clear pathway towards orders-of-magnitude improved experimental sensitivity to \(P,T\) violating physics.