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ABSTRACT:
Atomic stabilization is a highlight of superintense laser-atom
physics.
Its theory illustrates the methods used in the field. With this in
mind, we
present a brief overview of the subject and its perspectives.
We discuss the two forms of stabilization, identified
theoretically,
"quasistationary stabilization" (QS) and
"dynamic stabilization" (DS).
The first one, QS, refers to the limiting case of a monochromatic plane
wave, and describes the fact that the ionization rate, as given by Floquet
theory, decreases with the intensity (possibly in an oscillatory manner)
beyond a certain high value of the intensity. We discuss the physical
origin
of the phenomenon based on the high-frequency Floquet theory (HFFT). We
evaluate the accurate results obtained for QS.
The alternative form, DS, expresses the fact that the atomic
ionization
probability at the end of a laser pulse of fixed shape and duration,
does
not tend to 1 (complete ionization) as the peak intensity is
increased, but
it either decreases with the intensity (possibly in an oscillatory
manner),
or flattens out at a value smaller than 1. We mention some of the results
obtained for DS with 1D models, used because they do not require excessive
computation. However, very recently, progress in computation have allowed
the comprehensive mapping out of the 3D problem for hydrogen. We interpret
the results on the basis of "multistate Floquet theory".
This allows a
unified description of DS, and of the transition from the adiabatic
regime
to that of short pulses.
We mention thereafter the experimental evidence in favor of the
phenomenon,
and the necessity of extending it. This has become timely, due to
the
advent of adequate new light sources, like the VUV FEL at DESY,
and
attosecond pulses obtained from high harmonic generation. We finally
describe a proposal at DESY for a DS experiment on the ground state of
atomic Li.
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