Faculty of Physics - University of Bucharest

UNIVERSITY OF BUCHAREST
FACULTY OF PHYSICS

Guest
2024-11-24 23:08

HOME CONFERENCES SEARCH LOGIN NEW USER IMAGES

Conference: Bucharest University Faculty of Physics 2013 Meeting

Section: Theoretical Physics and Applied Mathematics

Title:

Relativistic effects in atom-laser interaction

Authors:

Madalina Boca and Viorica Florescu

Affiliation:

Faculty of Physics, University of Bucharest

E-mail

vdflor39@yahoo.com

Keywords:

Laser-atom; Floquet states, relativistic effects

Abstract:

We present an application of a recently published relativistic generalization of the Kramers-Henneberger transformation, according to which in the case of initially low energy electrons the Dirac equation in the presence of an atomic potential V and a very intense electromagnetic pulsed wave is equivalent to a Schrodinger-like equation which includes in a modified time dependent atomic potential both the atomic potential V and the external field action.For this Schrodinger equation, whose Hamiltonian is periodic in time if the laser field is monochromatic, we discuss the Floquet problem and calculate the quasienergy of the dressed ground state. In this purpose, we integrate the Schrodinger equation for a laser pulse consisting in a very long turn-on, followed by a constant amplitude part. The initial state of the electron is the ground state in the atomic potential V. During the turn-on the wave function evolves adiabatically, being at any moment the (intensity dependent) Floquet state originating from the initial stationary state. Next, during the constant part of the field, the electron remains in the Floquet state. We show how the real and imaginary parts of the quasienergy can be extracted from the autocorrelation of the wavefunction. The numerical integration of the Schrodinger equation is performed on a cartesian grid, using the split-operator method. We present results for a two-dimensional model system and for the realistic three dimensional Coulomb potential. In the latter case, we compare our results with those predicted by the non relativistic high frequency Floquet theory.