Quantum beat spectroscopy: Stimulated emission probe of hyperfine quantum beats in the atomic cesium

Measurements of hyperfine polarization quantum beats are used to determine the magnetic dipole ($A$) and electric quadrupole ($B$) coupling constants in the excited atomic Cs $8p\,^2P_{3/2}$ level. The experimental approach is a combination of pulsed optical pumping and time-delayed stimulated-emission probing of the excited level. From the measured evolution of the atomic linear polarization degree as a function of probe delay time, we determine the hyperfine coupling constants $A$ = 7.42(6) MHz and $B$ = 0.14(29) MHz.