  This work sets a road-map towards an experimental realization of strong
coupling between free-electrons and photons, and analytically explores
entanglement phenomena that emerge in this regime. The proposed model unifies
the strong-coupling predictions with known electron-photon interactions.
Additionally, this work predicts a non-Columbic entanglement between freely
propagating electrons. Since strong-coupling can map entanglements between
photon pairs onto photon-electron pairs, it may harness electron beams for
quantum communication, thus far exclusive to photons.
