The permanent electric dipole moment (EDM) of atoms, molecules, and elementary particles is predicted in the standard model. While it is too small compared with the experimental measurement sensitivity, it is an important method to search for beyond-standard-model physics via CP violating mechanisms. In this talk, I will focus on the EDM measurement of the 171Yb atoms with atoms held in an optical dipole trap. A quantum nondemolition measurement with a spin-detection efficiency of 50% is realized. A systematic effect due to parity mixing induced by a static E field is observed, and is suppressed by averaging between measurements with optical dipole traps in opposite directions. The coherent spin precession time is found to be much longer than 300 s. The measurement result leads to an upper limit of |d(171Yb)| < 1.5 E−26 e cm (95% C.L.). These measurement techniques can be adapted to search for the EDM of 225Ra.
|