An atomic magnetometer is used to detect radio frequency magnetic fields, such as those generated in nuclear resonance experiments. The magnetometer is based on nonlinear magneto-optical rotation and pumps an atomic vapor into a quadrupole aligned state. Detection of the modulation of the polarization of a linearly polarized beam provides the radio frequency signal, which can then be processed to extract the component frequencies.
STATEMENT REGARDING FEDERALLY SPONSORED R&D
 The U.S. Government has a paid-up license in this invention and the right in limited circumstances to require the patent owner to license others on reasonable terms as provided for by the terms of Contract No. DE-AC02-05CH11231 awarded by the Department of Energy.