The role of reflections in the generation of a time delay in strong field ionization

Abstract

The problem of time delay in tunneling ionization is revisited. The origin of time delay at the tunnel exit is analysed, underlining the two faces of the concept of the tunnelling time delay: the time delay around the tunnel exit and the asymptotic time delay at a detector. We show that the former time delay, in the sense of a delay in the peak of the wavefunction, exists as a matter of principle and arises due to the sub-barrier interference of the reflected and transmitted components of the tunneling electronic wavepacket. We exemplify this by describing the tunnelling ionization of an electron bound by a short-range potential within the strong field approximation in a "deep tunnelling" regime. If sub-barrier reflections are extracted from this wavefunction, then the time delay of the peak is shown to vanish. Thus, we assert that the disturbance of the tunnelling wavepacket by the reflection from the surface of the barrier causes a time delay in the neighbourhood of the tunnel exit.

14 pages, 11 figures

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• Attoclock revisited on electron tunnelling time
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Cited by in corpus (4)

• Attosecond Ionization Time Delays in Strong-Field Physics
• Reconciling conflicting approaches for the tunneling time delay in strong field ionization
• Sub-barrier recollisions and the three classes of tunneling time delays in strong-field ionization
• Formulation of causality-preserving quantum time of arrival theory