A 3He-21Ne Co-magnetometer for searching Spin-Gravity Interactions

Nuclear spin co-magnetometry provides exceptional precision in resolving spin energy levels and offers the potential for long-term stability, making it a promising platform for testing spin-dependent physics beyond the Standard Model. We report recent advancements in a Ramsey-type pulsed $^{3}He-^{21}Ne$ co-magnetometer, including the implementation of a microwave field to suppress Rb polarization, effectively replacing fast Rb spin-flip pulses and significantly reducing the associated Bloch-Siegert frequency shift. We investigate systematic errors induced by Ramsey pulses for nuclear spin and fast Rb spin-flip pulses and microwave field, which could significantly impact future searches for spin-gravity couplings.