Progress on the JILA Gen. III electron's Electric Dipole Moment (eEDM) Experiment

A nonzero value of the electron’s electric dipole moment (eEDM) would violate CP symmetry. Therefore, a measurement with improved sensitivity can provide insight on physics beyond the Standard Model. Using molecular ions HfF⁺, the second generation of the JILA eEDM experiment recently reported the most precise measurement of the eEDM, d_e = (-1.3±2.0_stat±0.6_syst) x 10^-30 e cm [1,2]. To improve upon this precision, the third generation of the experiment utilizes ThF⁺ whose eEDM sensitive state promises coherence time of ~20 seconds [3,4,5]. To fully take advantage of the long coherence time, one must decouple the repetition time of the experiment from the long coherence time. We plan to make a “conveyor belt” of 25 consecutive ion traps named the Bucket Brigade (B.B.), which will continuously load, state evolve, and read out ThF⁺, allowing for an increased repetition rate without compromising long interrogation times. We are currently studying a prototype of the Bucket Brigade at a reduced scale. Here, we present our progress towards a more sensitive measurement of the eEDM, including improved state detection and quasi-continuous-mode precision measurement with a long coherence time.

[1] Roussy, Tanya S., et al. Science 381, 46-50 (2023).

[2] Caldwell, Luke, et al. Physical Review A 108 (2023): 012804

[3] Gresh, Daniel N., et al. Journal of Molecular Spectroscopy 319 (2016): 1-9.

[4] Zhou, Yan et al. J. Mol. Spec. 358, (2019) 1-16

[5] Ng, Kia Boon et al. Physical Review A 105 (2022): 022823