Two-atom Coherent Response during Resonant X-ray Scattering of Intense Attosecond Pulses

The two-atom coherent response during resonant elastic x-ray scattering from high intensity attosecond pulses is theoretically studied. The scattering response from two-similar non-interacting atoms using a sample system of Ne⁺ is used to obtain insights about the scaling of the scattering signal with the number of atoms. The effect of rabi oscillations between core-hole and valence-hole states as well as the depletion of electrons due to photoionization and Auger decay are included. The dependence of the resonant scattering signal on the scattering angle, outgoing photon polarization, incident pulse intensity and the separation between the atoms is investigated. For high intensities, the resonant fluorescence channel and elastic scattering channel are found to exhibit different scaling with the number of atoms. While the elastic scattering signal is found to scale largely with the square of the number of atoms, the scaling of the resonant fluorescence signal is found to have a rich dependence on the final scattered quantum state.