Dynamic Stark effect and forbidden-transition spectral line shapes (13 pages)

Guy Michel Stéphan

D. T. Pegg

J. E. Stalnaker, Dmitry Budker, S. J. Freedman +3 more

We report on an experimental and theoretical study of the dynamic (ac) Stark effect on a forbidden transition. A general framework for parametrizing and describing off-resonant ac-Stark shifts is presented. A model is developed to calculate spectral line shapes resulting from resonant excitation of atoms in an intense standing light wave in the presence of off-resonant ac-Stark shifts. The model is used in the analysis and interpretation of a measurement of the ac-Stark shifts of the static-electric-field-induced $6{s}^{2}\phantom{\rule{0.2em}{0ex}}^{1}S_{0}\ensuremath{\rightarrow}5d6s^{3}D_{1}$ transition at $408\phantom{\rule{0.3em}{0ex}}\mathrm{nm}$ in atomic Yb. The results are in agreement with estimates of the ac-Stark shift of the transition under the assumption that the shift is dominated by that of the $6{s}^{2}\phantom{\rule{0.2em}{0ex}}^{1}S_{0}$ ground state. A detailed description of the experiment and analysis is presented. A biproduct of this work is an independent determination (from the saturation behavior of the 408-nm transition) of the Stark transition polarizability, which is found to be in agreement with our earlier measurement. This work is part of the ongoing effort aimed at a precision measurement of atomic parity-violation effects in Yb.

Gennady A. Koganov, R. Shuker

We show that initially dipole-forbidden atomic transitions can be effectively controlled by bichromatic laser fields. Such transitions become dynamically allowed due to ac-Stark effect. Gain, dispersion and spectral properties of these transitions are discussed.

Joachim Oxenius, E. Simonneau

Minora Hashimoto, Motoichi Ohtsu

Novel spectral line shapes of optical-microwave double resonance with an extremely narrow line width were observed in a rubidium atomic clock pumped by a semiconductor laser. It was confirmed that these novel spectral line shapes of double resonance were due to the modulation-transfer effect. These spectral line shapes were calculated by solving the equation of motion of the density matrix that describes the modulation-transfer process. The calculated results agree with the experimental results. By using the calculated results of the influence of the optical Stark effect on these spectral line shapes, characteristics of the inhomogeneous light shift were evaluated quantitatively for the frequency-modulated microwave. Furthermore, optimum values of modulation parameters were found by computer simulation in order to obtain the highest microwave frequency stability of the atomic clocks. An experiment was carried out employing these optimum parameters, and a short-term frequency stability as high as σy(τ) = 7.9 × 10−13τ−1/2 was obtained, where τ is an integration time of measurement.