Proposed search for an electric - dipole moment using laser - cooled 171 Yb atoms

We propose an experiment to search for a permanent atomic electric-dipole moment (EDM) using laser-cooled Yb atoms launched in an atomic fountain. A uniform B field sets the quantization axis, and the Ramsey separated-oscillatory-fields method is used to measure the Zeeman precession frequency of the atoms. Laser beams of appropriate polarization are used for preparation and detection in a given magnetic sublevel. The signature of an EDM is a shift in the Ramsey resonance correlated with application of a large E field. The precision is expected to be at least 20 times better than current limits because the use of a cold atomic beam allows application of E field 10 times larger than in a vapor cell, and the interaction time with the E field is 200 times larger compared to a thermal beam. The leading source of systematic error in beam experiments, the E × v/c motional magnetic field, is reduced considerably because of the near-perfect reversal of velocity between up and down trajectories through the E-field region. PACS. 32.80.Pj Optical cooling of atoms; trapping – 32.10.Dk Electric and magnetic moments, polarizability – 11.30.Er Charge conjugation, parity, time reversal, and other discrete symmetries