Anna Korver

Synchronous Spin-Exchange Optical Pumping.

We demonstrate a new approach to precision NMR with hyperpolarized gases designed to mitigate NMR shifts due to the alkali spin-exchange field. The NMR bias field is implemented as a sequence of alkali (Rb) 2π pulses, allowing the Rb polarization to be optically pumped transverse to the bias field. When the Rb polarization is modulated at the noble-gas (Xe) NMR resonance, spin-exchange collisions buildup a precessing transverse Xe polarization. We study and mitigate novel NMR broadening effects due to the oscillating spin-exchange field. Spin-exchange frequency shifts are suppressed 2500×, and Rb magnetometer gain measurements project photon shot-noise limited NMR frequency uncertainties below 10  nHz/sqrt[Hz].

Synchronously pumped NMR gyro

We are implementing a new design for spinexchange- pumped NMR gyros that addresses the key systematic errors as compared to previous implementations. The key concept is to drive magnetic resonance using spin-exchange collisions in a reference frame rotating about a bias magnetic field. The resulting purely transverse polarization is predicted to be insensitive to spin-exchange field shifts and quadrupole interactions, both of which are prominent in designs based on conventional magnetic resonance. Preliminary studies have identified a novel type of spin-exchange broadening that can be compensated to allow the system to reach T1-limited line width.