Entanglement and photoelectron holography in dissociative photoionization: molecular quantum eraser

TL;DR

This study demonstrates quantum entanglement and which-way information erasure in molecular photoionization, revealing how interference patterns are affected by entangled states and how they can be restored through state selection.

Contribution

It provides experimental evidence of entanglement in dissociative photoionization and shows how quantum erasure restores interference in a molecular system.

Findings

Correlated emission directions indicate entanglement between photoelectron and residual ion.

Interference fringes are suppressed by which-way information and restored by state selection.

Numerical simulations support the experimental observations.

Abstract

In a double-slit experiment with a bipartite system, the visibility of interference fringes depends on the availability of which-way information. Here, we report the formation of a Bell-like state of photoelectron and residual ion in the multiphoton dissociative ionization of the D$_2$ molecule. Evidence for entanglement is provided by the correlated emission directions of photoelectron and ion, which is observed using a COLTRIMS reaction microscope. In the presence of this correlation, the holographic interference fringes contained in the photoelectron momentum distributions are suppressed, indicating the existence of which-way information. We show that the which-way information is erased, and the interference pattern is restored, when a single ionic state is selected. The experimental observations and conclusions are fully supported by the numerical solution of the electronic-nuclear time-dependent Schr\"odinger equation. Our work demonstrates that coincidence spectroscopy of ions and electrons is a powerful method for studying fundamental concepts of quantum information science within the context of ultrafast light-matter interactions.