Fast extraction of the electron spin-relaxation rate in the SERF magnetometer from a transient response

The magnitude of the electron spin-relaxation rate R_rel of the atomic ensemble directly affects the sensitivity of the spin-exchange relaxation-free (SERF) atomic magnetometer (AM). The rapid and in-situ characterization of R_rel is of great importance. In this work, a fast extraction method of R_rel is proposed with a measurement period shorten to 0.5 s, merely detecting the transient response of SERF AM to a transverse DC excitation magnetic field after switching off the pump beam. In contrast to the conventional methods based on the measurement of the magnetic resonance linewidth, this method circumvents the involvement of optical pumping rate, and enables monitoring R_rel under arbitrary polarization, which is expected to improve the authenticity of R_rel measurement in a more convenient way.