Kia Boon Ng

We discuss the experimental realization of the rotating radio-frequency (rrf) trap, proposed by Hasegawa and Bollinger [Phys. Rev. A 72, 043403 (2005)]. Compared to a traditional linear rf (lrf) Paul trap, the rrf trap is a closer analogy to the popular mechanical lecture demonstration for a Paul trap. In an ion trap with reslistic, non-ideal electrode geometry, the rrf trap averages over angular variations in the effective potential. This averaging provides more uniform confinement and reduces ion loss at equal confinement strength compared with the lrf trap. This feature makes the rrf trap configuration advantageous for precision metrology application, such as electron electric dipole moment (eEDM) measurements.

Efficient quantum-state detection is crucial for many precision control experiments, such as the ongoing effort to probe the electron's electric dipole moment using trapped molecular $^{232}\mathrm{ThF}^+$ ions at JILA. While quantum state detection through state-selective photodissociation has been successfully implemented on this molecule, progress has been hindered by low dissociation efficiency. In this work, we perform spectroscopy on the molecule to identify excited states that facilitate more efficient photodissociation. For the most favorable transition, we achieve a dissociation efficiency of 57(14)% with quantum state selectivity. Additionally, we discuss several state detection protocols that leverage favorable excited states that will facilitate simultaneous readout of all EDM relevant states, allowing further improvement of overall statistics.

Cold molecules provide an excellent platform for quantum information, cold chemistry, and precision measurement. Certain molecules have enhanced sensitivity to beyond Standard Model physics, such as the electron's electric dipole moment ($e$EDM). Molecular ions are easily trappable and are therefore particularly attractive for precision measurements where sensitivity scales with interrogation time. Here, we demonstrate a spin precession measurement with second-scale coherence at the quantum projection noise (QPN) limit with hundreds of trapped molecular ions, chosen for their sensitivity to the $e$EDM rather than their amenability to state control and readout. Orientation-resolved resonant photodissociation allows us to simultaneously measure two quantum states with opposite $e$EDM sensitivity, reaching the QPN limit and fully exploiting the high count rate and long coherence.