Hannover 2010 – wissenschaftliches Programm
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A: Fachverband Atomphysik
A 8: Poster I
A 8.16: Poster
Dienstag, 9. März 2010, 16:30–19:00, Lichthof
Extension of imaginary time method for laser assisted tunneling of quasistationary states — •Héctor M. Castañeda1, Sergey Popruzhenko2, Adriana Pálffy1, and Christoph H. Keitel1 — 1Max-Planck-Institut für Kernphysik, Heidelberg, Germany — 2Moscow State Engineering Physics Institute, Russia
The imaginary time method (ITM) [1] was originally introduced for description of nonlinear ionization in intense laser fields, or, in general, tunneling through time-dependent barriers [2]. Within ITM, the ionization process is described by classical equations of motion solved in complex time, so that the transition amplitude is determined by the respective classical action [1,2].
For atoms in the absence of an external field, the initial state is usually a true bound state and the electron cannot tunnel out freely. However, laser fields can also assist processes where tunneling occurs already without an external field, such as cold emission of electrons or decay of autoionizing states. For description of such intense-laser-assisted effects, ITM could also serve as an efficient tool. Here we extend the formalism of ITM to describe laser-assisted decay of quasistationary states and apply it to calculate the tunneling probability in the presence of an intense electromagnetic field. We show that the laser field modifies the total probability of decay and the shape of the spectrum. This opens a way to control the quasistationary state decay.
[1] V. S. Popov, V. P. Kuznetsov, and A. M. Perelomov, JETP 26, 222 (1967)
[2] V. S. Popov, Phys. At. Nucl. 68, 686 (2005)