Causality and quantum interference in time-delayed laser-induced nonsequential double ionization

Shaaran, Tahir and Figueira de Morisson Faria, C. and Schomerus, Henning (2012) Causality and quantum interference in time-delayed laser-induced nonsequential double ionization. Physical review a, 85 (2): 023423. ISSN 1050-2947

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We perform a detailed analysis of the importance of causality within the strong-field approximation and the steepest-descent framework for the recollision-excitation with subsequent tunneling ionization (RESI) pathway in laser-induced nonsequential double ionization (NSDI). In this time-delayed pathway, an electron returns to its parent ion and, by recolliding with the core, gives part of its kinetic energy to excite a second electron at a time t′. The second electron then reaches the continuum at a later time t by tunneling ionization. We show that, if t′ and t are complex, the condition that recollision of the first electron occurs before tunnel ionization of the second electron translates into boundary conditions for the steepest-descent contours and thus puts constraints on the saddles to be taken when computing the RESI transition amplitudes. We also show that this generalized causality condition has a dramatic effect on the shapes of the RESI electron momentum distributions for few-cycle laser pulses. Physically, causality determines how the dominant sets of orbits of an electron returning to its parent ion can be combined with the dominant orbits of a second electron tunneling from an excited state. All features encountered are analyzed in terms of such orbits and their quantum interference.

Item Type:
Journal Article
Journal or Publication Title:
Physical review a
Additional Information:
©2012 American Physical Society
Uncontrolled Keywords:
?? physicsatomic and molecular physics, and opticsqc physicsdiscipline-based research ??
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Deposited On:
13 Mar 2012 09:05
Last Modified:
15 Jul 2024 12:40