Optical magnetometer: Quantum resonances at pumping repetition rate of 1/n of the Larmor frequency.

The response of a spin exchange relaxation free atomic magnetometer to a repetitive short-pulsed pump was investigated. Quantum sub-resonances at a repetition rate of 1/n of the Larmor frequency of the magnetic field inside the shield are experimentally observed and theoretically explained. This is a type of synchronization phenomenon. Investigations in single alkali atom cells and mixed alkali atoms of K and Rb are presented. In the latter, one species is pumped while the probe is on the other species polarized by spin exchange. The effect of spin destruction, spin exchange, and collisions is studied in order to account for the width of the resonances. Quantum calculations of a three-level Λ model for this phenomenon exhibit a dip at the resonance frequency in the absorption spectrum for both cases of pulsed and cw pump modes and an evidence for electromagnetically induced transparency. [ABSTRACT FROM AUTHOR]