He nuclear-spin oscillator for detection of exotic spin couplings*

We describe a ³He nuclear-spin oscillator that uses feedback to self oscillate in the presence of a leading magnetic field.  Hybrid pumping of Rb atoms is used to polarize K and ³He spins in a vapor cell through spin-exchange collisions.  The nuclear spins are tipped to start their precession about the leading field.  The precession is detected via optical rotation of light detuned from the D1 transition in K. This signal is fed back to magnetic field coils surrounding the cell to sustain the oscillation of the ³He spins.  We investigate the sensitivity of this system to the measurement of exotic spin couplings for potential application to the Global Network of Optical Magnetometers for Exotic physics (GNOME).