Quantification of entanglement entropies for doubly excited resonance states in two-electron atomic systems

In this work, we study the quantum entanglement for doubly excited resonance states in two-electron atomic systems such as the H-and Ps-ions and the He atom by using highly correlated Hylleraas type functions The resonance states are determined by calculation of density of resonance states with the stabilization method. The spatial (electron-electron orbital) entanglement entropies (linear and von Neumann) for the low-lying doubly excited states are quantified using the Schmidt-Slater decomposition method.