Development of a novel comagnetometer for high-precision measurement of the electron's electric dipole moment using laser-cooled francium atoms

In this presentation, the current status of a comagnetometer which is dedicated to search for the permanent electric dipole moment of the electron (eEDM) using francium (Fr) wll be discussed. The dominant error factors are Zeeman shift caused by the fluctuation of the static magnetic field and vector light shift caused by the ellipticity of the laser light forming the optical lattice in measuring the eEDM with laser-cooled Fr atoms. The designed comagnetometer consists of laser-cooled Rb-87 and Cs-133 atoms trapped simultaneously in the optical lattice at the same region where Fr atoms are trapped and a stable magnetic field is produced by superconducting coils in order to observe the effects of Zeeman shift and vector light shift independently. This is expected to increase the measurement precision of the eEDM, consequently allows to search for the CP violation with high precision.