  The triaxial-vectorial magnetic field measurement method based on the
quasi-steady-state solution of Bloch equation for SERF atomic magnetometry is
firstly proposed by S. Seltzer and M. Romalis in 2004, which introduces
dual-axis zero-crossing magnetic fields modulation. The modulation frequency
must be slow enough that the quasi-steady-state solution is valid, otherwise
the measurement accuracy will be seriously degraded. Thus the bandwidth of the
system is greatly limited. In order to enhance the bandwidth constricted by the
range of modulation frequency, we investigate the response of alkali-atomic
spin to high-frequency modulation field by solving the Bloch equation in a
time-dependence manner.
