Long-time joint spectra and entanglement of two photoelectrons originating in interacting auto-ionization systems

Two auto-ionization systems in a stationary optical field that are mutually interacting via the dipole–dipole interaction are considered. Their evolution is found analytically. Joint spectra of two ionized electrons are analyzed in detail in the long-time limit for comparable strengths of direct and indirect ionization paths as well as the dominating indirect ionization path. Entanglement in the state of two ionized electrons is quantified using the density of quadratic negativity. Suitable conditions for obtaining highly entangled states are discussed. (paper)