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キーワード:
-
MPINP:
Research group K. Z. Hatsagortsyan – Division C. H. Keitel
要旨:
Tunnel-ionization is investigated in the framework of relativistic quantum mechanics.
For an arbitrary constant electromagnetic field a gauge invariant energy
operator is introduced in order to identify the classically forbidden region for
tunnel-ionization. Furthermore, relativistic features of tunnel-ionization are explored.
A one-dimensional intuitive picture predicts that the ionized electron wave
packet in the relativistic regime experiences a momentum shift along the laser’s
propagation direction. This is shown to be consistent with the well-known strong
field approximation. Furthermore, spin dynamics in tunnel-ionization process
is discussed in the standard as well as in the dressed strong field approximation.
Next, the tunneling time delay is investigated for tunnel-ionization by extending
the definition of the Wigner time delay. Later, this concept is redefined in terms of
the phase of the fixed energy propagator. The developed formalism is applied to
the deep-tunneling and the near-threshold-tunneling regimes. It is shown that in
the latter case signatures of the tunneling time delay can be measurable at remote
distance. Finally, the path-dependent formulation of gauge theory is discussed. It
is demonstrated that this equivalent formulation of gauge theory leads to a canonical
gauge fixing, in which the Feynman path integral becomes more intuitive and
the calculation of the quasiclassical propagator is considerably simplified.
