title: Synchronous Spin-Exchange Optical Pumping.
abstract: 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].
authors.affiliation: Department of Physics, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA.
authors.forename: A
authors.initials: A
authors.lastname: Korver
authors.affiliation: Department of Physics, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA.
authors.forename: D
authors.initials: D
authors.lastname: Thrasher
authors.affiliation: Department of Physics, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA.
authors.forename: M
authors.initials: M
authors.lastname: Bulatowicz
authors.affiliation: Department of Physics, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA.
authors.forename: T G
authors.initials: TG
authors.lastname: Walker