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 to determine the magnetic dipole (A) and electric quadrupole (B) coupling constants in the excited atomic Cs $8p{}^2{P}_{3/2}$ 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 $A=7.42\left(6\right)$ MHz and $B=0.14\left(29\right)$ MHz.

Figure 1

Partial energy-level diagram for atomic Cs, showing the excitation (solid line) and detection (dotted line) transitions used in the experiment.

Figure 2

A schematic view of the experimental apparatus. In the figure GT stands for a Glan-Thompson polarizer, PMT for a photomultiplier tube, and LCR for a liquid-crystal retarder.

Figure 3

Quantum beats are experimentally observed from the pump-stimulated-emission probe spectroscopy. The probe-delay-time dependence of the linear polarization degree, showing the hyperfine quantum beats in the excited level, is indicated by the data points. The result of the best fit to the data is the solid line.

Figure 4

Distribution of the residuals of the fit of the linear polarization as a function of probe delay time. Each residual is normalized to the experimental estimated uncertainty in the individual data point. The solid horizontal line represents the average value of the residuals, while the dashed horizontal lines indicate the normalized $1\sigma$ levels.