Certifying the quantumness of a generalized coherent control scenario

Abstract

We consider the role of quantum mechanics in a specific coherent control scenario, designing a "coherent control interferometer" as the essential tool that links coherent control to quantum fundamentals. Building upon this allows us to rigorously display the genuinely quantum nature of a generalized weak-field coherent control scenario (utilizing 1 vs. 2 photon excitation) via a Bell-CHSH test. Specifically, we propose an implementation of "quantum delayed-choice" in a bichromatic alkali atom photoionization experiment. The experimenter can choose between two complementary situations, which are characterized by a random photoelectron spin polarization with particle-like behavior on the one hand, and by spin controllability and wave-like nature on the other. Because these two choices are conditioned coherently on states of the driving fields, it becomes physically unknowable, prior to measurement, whether there is control over the spin or not.

Polarized photoelectrons from converging vector waves

“…will no doubt address 'nonideal' effects, such as multimode irradiation, which may not necessarily be deleterious. For example, it has been shown that interference of the ionization paths in the presence of a photoionizing laser field and its second harmonic leads to the possibility of coherent control of the spin of the photoelectron [62,63].…”

An Approach To “Quantumness” In Coherent Control

“…5 can be implemented with a combination of Eqs. ( 134), (136) and (141). The existence of a single direction of detection K+ [Eq.…”

“…Here, we apply this formalism to a specific example used throughout the remainder of the article, phase-coherent control of the spin polarization of an electron emitted in an 1 vs. 2 photoionization process from a heavy alkali atom [136]. This control scenario is an extension of Elliott's twocolor photoionization experiments on alkali atoms [14,15,32,33], which demonstrated that the angular distribution of an emitted photoelectron can be controlled by the relative phase between two ionizing laser beams.…”