Speaker
Description
Searches for permanent electric dipole moments (EDMs) probe new sources of CP violation beyond the Standard Model. The atomic EDM of 171Yb, which arises from its nuclear Schiff moment, is a promising candidate, but previous measurements were limited by noise and systematics induced by the optical dipole trap (ODT) that holds the atoms. Here we report a substantially improved search enabled by a dual-ODT configuration with orthogonal polarizations, and spin measurements for precise alignment of static and optical fields. By suppressing the dominant parity-mixing systematic and vector light-shift noise, we achieve a limit of |d(171Yb)| < 7.5 × 10−28 e · cm (95% C.L.), which represents a 20-fold improvement over the previous work. We also present
the first nuclear-structure calculation of the 171Yb Schiff moment. The experimental and theoretical advances combine to tighten constraints on CP-violating pion-nucleon couplings in a global analysis. Moreover, this work demonstrates a pathway toward future measurements in 225Ra, where nuclear deformation offers exceptional sensitivity to physics beyond the Standard Model.