3He-129Xe Comagnetometery using 87Rb Detection and Decoupling

We describe a He-3-Xe-129 comagnetometer using Rb-87 atoms for noble-gas spin polarization and detection. We use a train of Rb-87 pi pulses and sigma(+)/sigma(-) optical pumping to realize a finite-field Rb magnetometer with suppression of spin-exchange relaxation. We suppress frequency shifts from polarized Rb by measuring the He-3 and Xe-129 spin precession frequencies in the dark, while applying pi pulses along two directions to depolarize Rb atoms. The plane of the pi pulses is rotated to suppress the Bloch-Siegert shifts for the nuclear spins. We measure the ratio of He-3 to Xe-129 spin precession frequencies with sufficient absolute accuracy to resolve Earth's rotation without changing the orientation of the comagnetometer. A frequency resolution of 7 nHz is achieved after integration for 8 h without evidence of significant drift.