The molecular quantum eraser

By sending ultrashort strong laser pulses onto Deuterium molecules (D₂) they get ionized, and subsequently the resulting D₂⁺ molecular ion breaks up into a Deuterium atom and a D⁺ ion. By detecting the photoelectron and D⁺ ion in coincidence and with spatial and energetic resolution, a team researchers at the Institute for Optics and Quantum Electronics (IOQ) and IFTO, together with collaborators form Hannover and Sarajevo, could show that entanglement is generated in this process. When focusing at the right energy window of the produced fragments, the ionization happens in a superposition between two paths associated with different symmetries of the dissociation products. We could reveal the resulting entanglement by measuring correlations between the emission directions of the dissociation products. Moreover, interference fringes showing up in the angular distribution of the photoelectrons get suppressed in the presence of entanglement, much like in the quantum eraser experiment in quantum optics, where “which path information” ion the form of entanglement prevents quantum interference.

Link to preprint: https://arxiv.org/abs/2604.16107External link