Resonances in the Excitation Functions of Atoms

The relative optical excitation functions and polarizations of the Sr resonance line (4607 \AA{}) and of the ${\mathrm{Sr}}^{+}$ resonance lines (4078 and 4216 \AA{}) have been measured, using crossed electron and strontium-atom beams, for electron energies from the excitation thresholds to 1497 eV. The electron-beam energy resolution was \ensuremath{\sim} 0.22 eV for energies below 13 eV, and the atom beam was optically thin. The excitation functions of the ionic lines were measured relative to that of the atomic resonance line at fixed energies near the maxima of the excitation functions. Using spontaneous-emission branching ratios, this yields the ratios of total excitation cross sections for the atomic and ionic resonance levels (including cascades). The Sr $5^{1}P$ excitation function has been normalized to Born theory taking account of cascade at 1497 eV, where the energy dependence of the excitation function has converged to the theoretical behavior. The resulting normalized cross sections have been compared with available theoretical calculations and other measurements. The 4607-\AA{} polarization function is consistent with the theoretical threshold limit within experimental uncertainity.The relative optical excitation functions and polarizations of the Sr resonance line (4607 \AA{}) and of the ${\mathrm{Sr}}^{+}$ resonance lines (4078 and 4216 \AA{}) have been measured, using crossed electron and strontium-atom beams, for electron energies from the excitation thresholds to 1497 eV. The electron-beam energy resolution was \ensuremath{\sim} 0.22 eV for energies below 13 eV, and the atom beam was optically thin. The excitation functions of the ionic lines were measured relative to that of the atomic resonance line at fixed energies near the maxima of the excitation functions. Using spontaneous-emission branching ratios, this yields the ratios of total excitation cross sections for the atomic and ionic resonance levels (including cascades). The Sr $5^{1}P$ excitation function has been normalized to Born theory taking account of cascade at 1497 eV, where the energy dependence of the excitation function has converged to the theoretical behavior. The resulting normalized cross sections have been compared with available theoretical calculations and other measurements. The 4607-\AA{} polarization function is consistent with the theoretical threshold limit within experimental uncertainity.

Physical Review AMar 1, 197627 citations

Resonant Excitation of Atoms

V. M. Akulin, Nikolai V. Karlov

Springer eBooksJan 1, 19920 citations

Coherent versus incoherent excitation dynamics in dissipative many-body Rydberg systems

David W. Schönleber, Martin Gärttner, Jörg Evers

We study the impact of dephasing on the excitation dynamics of a cloud of ultracold two-level Rydberg atoms for both resonant and off-resonant laser excitation, using the wave-function Monte Carlo technique. We find that while for resonant laser driving, dephasing mainly leads to an increase of the Rydberg population and a decrease of the Mandel $Q$ parameter, at off-resonant driving strong dephasing toggles between direct excitation of pairs of atoms and subsequent excitation of single atoms, respectively. These two excitation mechanisms can be directly quantified via the pair-correlation function, which shows strong suppression of the two-photon resonance peak for strong dephasing. Consequently, qualitatively different dynamics arise in the excitation statistics for weak and strong dephasing in off-resonant excitation. Our findings show that time-resolved excitation number measurements can serve as a powerful tool to identify the dominating process in the system's excitation dynamics.We study the impact of dephasing on the excitation dynamics of a cloud of ultracold two-level Rydberg atoms for both resonant and off-resonant laser excitation, using the wave-function Monte Carlo technique. We find that while for resonant laser driving, dephasing mainly leads to an increase of the Rydberg population and a decrease of the Mandel $Q$ parameter, at off-resonant driving strong dephasing toggles between direct excitation of pairs of atoms and subsequent excitation of single atoms, respectively. These two excitation mechanisms can be directly quantified via the pair-correlation function, which shows strong suppression of the two-photon resonance peak for strong dephasing. Consequently, qualitatively different dynamics arise in the excitation statistics for weak and strong dephasing in off-resonant excitation. Our findings show that time-resolved excitation number measurements can serve as a powerful tool to identify the dominating process in the system's excitation dynamics.

arXiv:1401.7260Physical Review AMar 19, 201437 citations

Lifetimes of highly excited atomic states

Houcem Jabri, Hichem Eleuch, Tahar Djerad

We consider a highly excited atom in a good cavity strongly pumped by coherent light. We derive the autocorrelation function of the field emergent from the cavity. We show that the autocorrelation function can be expressed in terms of the atomic dissipation rate. In order to distinguish between the resonant and the non-resonant case, we introduce a parameter interpreted as the measure of the relative detuning between the pump laser and the excited atom frequency. By selecting the parameter time, we determine the lifetime of the excited atom. This method constitutes an interesting alternative for internal atomic parameter determination.We consider a highly excited atom in a good cavity strongly pumped by coherent light. We derive the autocorrelation function of the field emergent from the cavity. We show that the autocorrelation function can be expressed in terms of the atomic dissipation rate. In order to distinguish between the resonant and the non-resonant case, we introduce a parameter interpreted as the measure of the relative detuning between the pump laser and the excited atom frequency. By selecting the parameter time, we determine the lifetime of the excited atom. This method constitutes an interesting alternative for internal atomic parameter determination.

Physica ScriptaMar 15, 200612 citations

On the Multiple Excitation of Atoms

K. I. Rozgachev, V. A. Fabrikant

Soviet physics. DokladyMay 1, 19570 citations

The relative optical excitation functions and polarizations of the Sr resonance line (4607 \AA{}) and of the

{\mathrm{Sr}}^{+}

resonance lines (4078 and 4216 \AA{}) have been measured, using crossed electron and strontium-atom beams, for electron energies from the excitation thresholds to 1497 eV. The electron-beam energy resolution was \ensuremath{\sim} 0.22 eV for energies below 13 eV, and the atom beam was optically thin. The excitation functions of the ionic lines were measured relative to that of the atomic resonance line at fixed energies near the maxima of the excitation functions. Using spontaneous-emission branching ratios, this yields the ratios of total excitation cross sections for the atomic and ionic resonance levels (including cascades). The Sr

5^{1}P

excitation function has been normalized to Born theory taking account of cascade at 1497 eV, where the energy dependence of the excitation function has converged to the theoretical behavior. The resulting normalized cross sections have been compared with available theoretical calculations and other measurements. The 4607-\AA{} polarization function is consistent with the theoretical threshold limit within experimental uncertainity.

Q

parameter, at off-resonant driving strong dephasing toggles between direct excitation of pairs of atoms and subsequent excitation of single atoms, respectively. These two excitation mechanisms can be directly quantified via the pair-correlation function, which shows strong suppression of the two-photon resonance peak for strong dephasing. Consequently, qualitatively different dynamics arise in the excitation statistics for weak and strong dephasing in off-resonant excitation. Our findings show that time-resolved excitation number measurements can serve as a powerful tool to identify the dominating process in the system's excitation dynamics.