Entanglement and Timing-Based Mechanisms in the Coherent Control of Scattering Processes

TL;DR

This paper explores how entanglement and timing influence the coherent control of scattering processes, specifically electron impact dissociation of H₂⁺, advancing theoretical understanding and proposing alternative control methods without entanglement.

Contribution

It provides a detailed analysis of entanglement-based and time-dependent coherent control mechanisms in reactive scattering, extending the theoretical framework and suggesting practical alternatives.

Findings

Entanglement ensures all collisions produce desired outcomes.

Time-dependent control can operate without initial entanglement.

Extended coherence features are crucial for control scenarios.

Abstract

The coherent control of scattering processes is considered, with electron impact dissociation of H$_2^+$ used as an example. The physical mechanism underlying coherently controlled stationary state scattering is exposed by analyzing a control scenario that relies on previously established entanglement requirements between the scattering partners. Specifically, initial state entanglement assures that all collisions in the scattering volume yield the desirable scattering configuration. Scattering is controlled by preparing the particular internal state wave function that leads to the favored collisional configuration in the collision volume. This insight allows coherent control to be extended to the case of time-dependent scattering. Specifically, we identify reactive scattering scenarios using incident wave packets of translational motion where coherent control is operational and initial state entanglement is unnecessary. Both the stationary and time-dependent scenarios incorporate extended coherence features, making them physically distinct. From a theoretical point of view, this work represents a large step forward in the qualitative understanding of coherently controlled reactive scattering. From an experimental viewpoint, it offers an alternative to entanglement-based control schemes. However, both methods present significant challenges to existing experimental technologies.