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We report on the operation of co-located 129 Xe and 131 Xe nuclear spin masers with an external feedback scheme, and discuss the use of 131 Xe as a comagnetometer in measurements of the 129 Xe spin precession frequency. By applying a correction based on the observed change in the 131 Xe frequency, the frequency instability due to magnetic field and cell temperature drifts are eliminated by two orders of magnitude. The frequency precision of 6.2 μHz is obtained for a 10 4 s averaging time, suggesting the possibility of future improvement to ≈ 1 nHz by improving the signal-to-noise ratio of the observation. [ABSTRACT FROM AUTHOR]

The technique of an active nuclear spin maser is adopted in the search for electric dipole moment in a diamagnetic atom Xe. 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 Xe spin, a He 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 Xe maser was reduced from 12 mHz to 700 μHz, and the determination precision of frequency of 8.7 nHz was obtained for a 2×10 s measurement time using the double-cell geometry cell. [ABSTRACT FROM AUTHOR]

Abstract: We have been developing a high sensitivity atomic magnetometer for atomic EDM experiments using a lowfrequency nuclear spin maser. In the developed nuclear spin maser of 129Xe, suppression of drift and fluctuation in the magnetic field is one of the important issues. The magnetometer being developed for spin maser EDM experiments utilizes the nonlinear magneto optical rotation (NMOR) e_ect in Rb atomic vapor. The enhancement of the optical rotation in a small magnetic field relies on the long spin-coherence time of Rb atoms in a vapor cell. The NMOR spectrum was measured by using fabricated Rb cells coated with an anti-relaxation material. The NMOR spectrum dependence on laser frequency, cell coating, and laser beam diameter were investigated. The magnetic sensitivity at present is 0:2μG/√Hz from observed NMOR and noise spectra. [Copyright &y& Elsevier]

Abstract: The development of a nuclear spin oscillator system, namely a spin maser with an external feedback, for use in the search for 129Xe atomic EDM is presented. By introducing a new current source for the B0 field solenoid, drifts in the maser frequency were remarkably suppressed. This in turn clearly brought out the correlation between the maser frequency and the environmental field. Correcting for the effect of the environmental field, the frequency precision of 5 nHz in the measurement time of 45,000s was attained. Origins of the remaining drifts in the maser frequency are now under investigation. [Copyright &y& Elsevier]

A nuclear spin maser of a new type, that employs a feedback scheme based on optical nuclear spin detection, has been fabricated. The spin maser is operated at a low static field of 30 mG by using the optical detection method. The frequency stability and precision of the spin maser have been improved by a highly stabilized current source for the static magnetic field. An experimental setup to search for an electric dipole moment (EDM) in 129Xe atom is being developed. [ABSTRACT FROM AUTHOR]

We describe a scheme for nuclear spin maser which has an artificial feedback to the nuclear spins to bring about a self-sustained nuclear spin precession and thus to allow unlimitedly long observation times for precession. This scheme can operate under lower applied fields and smaller spin densities than the conventional spin maser scheme. Its operation was experimentally tested by using a spin-polarized 129Xe gas as a model substance. The frequency fluctuation and other basic properties were analyzed based on the modified Bloch equations. [Copyright &y& Elsevier]