The fact that the universe is composed primarely of matter rather than being equal parts matter and anti-matter is described by the 2015 NSAC Long Range Plan as “one of the most compelling mysteries in all of science.” A matter-dominated universe requires significant violation of charge-conjugation parity (CP) symmetry, but we have not yet found any sufficiently strong sources. Searches for the electric dipole moment (EDM) of electrons, neutrons, and nuclei are sensitive probes of CP violation. However, no EDM has been observed to date, placing strong limits on the parameter space of beyond-the-standard-model theories.
Radium provides for a complementary probe to other ongoing and planned experiments. It is particularly sensitive to CP violation due to its unusual octupole deformation, enhancing radium’s would-be EDM by a large factor (hundreds to tens of thousands). The radium EDM experiment at Argonne is unique in its use of octupole deformations and the technique it uses to measure atomic EDMs. We have for the first time successfully used laser-cooled and trapped atoms to measure an EDM -- an achievement that paves the way for future experiments.
Our experiment is far from its systematic limit: we will leverage atomic physics techniques to greatly improve our sensitivity, an upcoming “Blue Light Upgrade” will greatly increase the system’s trapping efficiency, and future sources of radium at Los Alamos National Laboratory and the Facility for Rare Isotope Beams (FRIB) will increase the amount of radium available to the experiment. Through this multifaceted approach, we will reach a sensitivity 10,000 times better than the current state-of-the-art within 5-10 years. To reach even further, we are exploring a novel method using molecules containing radium, which may pave the way for next generation experiments with tremendous sensitivity to CP violation within nuclei.