Coherent Control and Entanglement in the Attosecond Electron Recollision Dissociation of D2+

TL;DR

This paper models and analyzes attosecond electron recollision dissociation of D2+ using a strong field approximation, demonstrating coherent control, wave-packet dynamics, and clarifying the role of entanglement in sub-femtosecond probing.

Contribution

It introduces a full dimensional SFA model for recollision dissociation, explores coherent control extensions, and clarifies the role of temporal correlations versus entanglement in ultrafast scattering.

Findings

The SFA model agrees with experimental results.

Recollision dissociation enables wave-packet coherent control.

Temporal correlations, not entanglement, are key for ultrafast resolution.

Abstract

We examine the attosecond electron recollision dissociation of D2+ recently demonstrated experimentally [H. Niikura et al., Nature (London) 421, 826 (2003)] from a coherent control perspective. In this process, a strong laser field incident on D2 ionizes an electron, accelerates the electron in the laser field to eV energies, and then drives the electron to recollide with the parent ion, causing D2+ dissociation. A number of results are demonstrated. First, a full dimensional Strong Field Approximation (SFA) model is constructed and shown to be in agreement with the original experiment. This is then used to rigorously demonstrate that the experiment is an example of coherent pump-dump control. Second, extensions to bichromatic coherent control are proposed by considering dissociative recollision of molecules prepared in a coherent superposition of vibrational states. Third, by comparing the results to similar scenarios involving field-free attosecond scattering of independently prepared D2+ and electron wave packets, recollision dissociation is shown to provide an example of wave-packet coherent control of reactive scattering. Fourth, this analysis makes clear that it is the temporal correlations between the continuum electron and D2+ wave packet, and not entanglement, that are crucial for the sub-femtosecond probing resolution demonstrated in the experiment. This result clarifies some misconceptions regarding the importance of entanglement in the recollision probing of D2+. Finally, signatures of entanglement between the recollision electron and the atomic fragments, detectable via coincidence measurements, are identified.