EDM measurement in ¹²⁹Xe atom using dual active feedback nuclear spin maser

The technique of an active nuclear spin maser is adopted in the search for electric dipole moment in a diamagnetic atom ¹²⁹Xe. In order to reduce systematic uncertainties arising from long-term drifts of the external magnetic field and from the contact interaction between longitudinal polarized Rb atoms and ¹²⁹Xe spin, a ³He comagnetometer with a double-cell geometry was employed. The remaining shift, which turned out to show some correlation with the cell temperature, was mitigated by stabilizing the cell temperature. As a result, the frequency drift of the ¹²⁹Xe maser was reduced from 12 mHz to 700 μHz, and the determination precision of frequency of 8.7 nHz was obtained for a 2×10⁴ s measurement time using the double-cell geometry cell.