EDM measurements on cold $^{\mathrm{225}}$Ra and $^{\mathrm{171}}$Yb atoms*

EDM measurements on diamagnetic atoms probe CP-violating effects in the nucleus. Some types of these Beyond-Standard-Model effects are known to be strongly enhanced in $^{\mathrm{225}}$Ra due to octupole deformation of the nucleus. Other favorable characteristics of $^{\mathrm{225}}$Ra include a high atomic number (Z $=$ 88), a ground state of $^{\mathrm{1}}$S$_{\mathrm{0}}$, and a nuclear spin 1/2. An EDM search is carried out on this radioactive isotope (half-life 15 d) using laser-cooled atoms. Meanwhile, $^{\mathrm{171}}$Yb is a stable isotope with atomic properties and transitions similar to those of $^{\mathrm{225}}$Ra, and is particularly useful as a proxy of $^{\mathrm{225}}$Ra for developing laser trapping and probing techniques, for testing various measurement schemes, and for investigating systematic errors. Moreover, $^{\mathrm{171}}$Yb atoms can be placed within 0.1 mm of $^{\mathrm{225}}$Ra, and act as a co-magnetometer. A laser trap of Yb atoms is under development towards an EDM measurement.