%0 Journal Article
%J Phys. Rev. A
%D 2010
%T Dipole spectrum structure of nonresonant nonpertubative driven two-level atoms
%A A. Picón
%A L. Roso
%A J. Mompart
%A O. Varela
%A V. Ahufinger
%A R. Corbalán
%A L. Plaja
%X We analyze the dipole spectrum of a two-level atom excited by a nonresonant intense monochromatic field under the electric dipole approximation and beyond the rotating wave approximation. We show that the apparently complex spectral structure can be completely described by two families: harmonic frequencies of the driving field and field-induced nonlinear fluorescence. Our formulation of the problem provides quantitative laws for the most relevant spectral features: harmonic ratios and phases, nonperturbative Stark shift, and frequency limits of the harmonic plateau. In particular, we demonstrate the locking of the harmonic phases at the wings of the plateau opening the possibility of ultrashort pulse generation through harmonic filtering.
%B Phys. Rev. A
%I American Physical Society
%V 81
%P 033420
%8 Mar
%U http://link.aps.org/doi/10.1103/PhysRevA.81.033420
%R 10.1103/PhysRevA.81.033420
%0 Journal Article
%J New Journal of Physics
%D 2010
%T Transferring orbital and spin angular momenta of light to atoms
%A A. Picón
%A A. Benseny
%A J. Mompart
%A J R Vázquez de Aldana
%A L. Plaja
%A G F Calvo
%A L. Roso
%X Light beams carrying orbital angular momentum (OAM), such as Laguerre–Gaussian (LG) beams, give rise to the violation of the standard dipolar selection rules during interaction with matter, yielding, in general, an exchange of angular momentum larger than ##IMG## [http://ej.iop.org/icons/Entities/planck.gif] {planck} per absorbed photon. By means of ab initio three-dimensional (3D) numerical simulations, we investigate in detail the interaction of a hydrogen atom with intense Gaussian and LG light pulses. We analyze the dependence of the angular momentum exchange with the polarization, the OAM and the carrier-envelope phase of light, as well as with the relative position between the atom and the light vortex. In addition, a quantum-trajectory approach based on the de Broglie–Bohm formulation of quantum mechanics is used to gain physical insight into the absorption of angular momentum by the hydrogen atom.
%B New Journal of Physics
%V 12
%P 083053
%U http://stacks.iop.org/1367-2630/12/i=8/a=083053