  Entanglement between two electrons belonging to an auto-ionization system and
a neighbor two-level atom produced by the dipole-dipole interaction is studied.
The entanglement is quantified using the quadratic negativity of a bipartite
system including the continuum of states. Suitable conditions for the
generation of highly entangled states of two electrons are revealed. Internal
structure of the entanglement is elucidated using the spectral density of
quadratic negativity.
