Quantum beat spectroscopy: stimulated emission probe of hyperfine   quantum beats in the atomic Cs 8p $^{2}P_{3/2}$ level
  Measurements of hyperfine polarization quantum beats are used determine the magnetic dipole (A) and electric quadrupole (B) coupling constants in the excited atomic Cs 8p level. The experimental approach is a novel 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. 
S.B. Bayram, P. Arndt, O.I. Popov, C. Guney, W.P. Boyle, M.D. Havey,   and J. McFarland
quant-ph physics.atom-ph