Second generation precision measurement of the electron’s electric dipole moment with trapped molecular ions

Precision measurements in atomic and molecular systems are complementary to studies with high-energy colliders in searches for physics beyond the standard model. Among these are measurements of permanent electric dipole moments (EDMs) of elementary particles, such as the electron, which constitute a low background probe of CP violation. The quantum state preparation and detection techniques developed for precision measurements with molecules may prove to be useful for a variety of applications ranging from quantum chemistry to quantum simulation.

In the second-generation measurement of the eEDM using trapped HfF⁺, the statistical uncertainty is projected to be competitive at 2 x 10⁻²⁹ e cm in one hour of integration time. To this end, we have attained a 2.5 second spin coherence time, and a 20-fold increase in count rate via optical pumping into states of opposite molecular orientation. We suppress technical noise by conducting a differential measurement of spatially separated photofragments arising from opposite molecular orientations, reaching the quantum projection noise limit. We will also discuss the progress towards a future measurement with ThF⁺molecules, where minute long spin precession times are predicted. By multiplexing these measurements, we project an overall 100-fold increase in sensitivity to the eEDM.