QED theory of laser-atom and laser-nucleus interaction

Full text: QED theory is developed for studying interaction of atoms and nuclei with an intense and superintense laser field. The method bases on a description of system in the field by the k-photon emission and absorption lines. The lines are described by their QED moments of different orders, which are calculated within Gell-Mann Low adiabatic formalism. The analogous S-matrix approach is developed for consistent description of the laser-nucleus interaction. We have studied the cases of single-, multi-mode, coherent, stochastic laser pulse shape. An account for stochastic fluctuations in a field effect is of a great importance. Results of the calculation for the multi-photon resonance and ionization profile in Na,Cs, Yb, Gd atoms are presented. The phenomenon of the above threshold ionization is also studied. Efficiency of the method is demonstrated by QED perturbation theory calculations for the two-photon ionization cross-sections for extended photon energy range (including above-threshold ionization) in Mg. Comparison with the R-matrix calculation of Luc-Koenig et al. is given. There is considered a phenomenon of the Rydberg stabilization of the H atom in a strong laser field and estimated the rate of transition between the stabilized Rydberg state (n=40, m=2; E 10(8) V/cm) and ground state, when it is possible the radiation of photons with very high energy (short-wave laser amplification). DC strong filed Stark effect for atoms, including atoms in plasma, Rydberg atoms and confined systems are studied within a new quantum approach, based on the operator PT. The zeroth order Hamiltonian, possessing only stationary states, is determined only by its spectrum without specifying its explicit form. We present here the calculation results of the Stark resonances energies and widths for a number of atoms (H, Li, Tm,U etc.) and for a whole number of low-lying and also Rydberg states. We discovered and analyzed the weak field effect of drastic broadening of widths of the Letokhov-Ivanov re-orientation decay autoionization resonances in Tm etc. The developed approach can be naturally applied to studying the Stark effect in confined systems, including quantum wells, quantum dots etc, where especially interesting effects may occur. (author)