US Patent 8373413 Magnetic sensing method, atomic magnetometer and magnetic resonance imaging apparatus

A magnetic sensing method comprises irradiating a pump light having a circularly polarized component and a probe light having a linearly polarized component onto a group of atoms contained in a cell so as to make the lights produce an intersection region and detecting a change of rotation angle of a plane of polarization of the probe light before and after passing the cell. The pump light and the probe light are irradiated in a state where a magnetic field of the direction in which the pump light strikes the intersection region is provided with a gradient.