Spatial entanglement in two-electron atomic systems

Abstract

Recently, there has been considerable interest in investigating quantum entanglement in two-electron systems, such as two-electron model atoms and quantum dots. In this work, the quantum entanglement of the helium atom and helium-like ions are explored using the two-electron wave functions constructed by the $B$-spline basis. As a measure of the spatial entanglement, the linear entropy of the reduced density matrix is investigated for the ground state and the singlet excited $1sn{s}^{1}S$ states, with $n=2$--10, of the helium atom. The variation of the spatial entanglement with the nuclear charges $Z=2$--15 for the helium-like ions is reported. Results are compared with the existing predictions.