Time Development of the Population Grating in Zeeman Sublevels in Sodium Vapor —Detection of Zeeman Quantum Beats

The population gratings were created by two intersecting resonant light pulses in the ground state 3²S_1⁄2 and the excited state 3²P_1⁄2 in sodium vapor, and their developements in a static magnetic field were monitored by the diffraction of the resonant probe pulse. Intensity modulations of the diffraction signals at the Zeeman frequencies (Zeeman beats) were observed, which are due to the oscillation of the LIPG's. The detailed analysis of the creation, detection and the time development of the LIPG was made in a simple model system with total angular momentum J=1⁄2 in both the ground and the excited states. The observed beat patterns were compared with the theoretical calculations including the effects of hyperfine interaction in both states. Polarization characteristics were also examined. The agreement between theoretical predictions and experimental results was quite satisfactory.