  We theoretically investigate the efficiency of an entanglement swapping
procedure based on the use of quantum dots as sources of entangled photon
pairs. The four-photon interference that affects such efficiency is potentially
limited by the fine-structure splitting and by the time correlation between
cascaded photons, which provide which-path information. The effect of spectral
inhomogeneity is also considered, and a possible quantum eraser experiment is
discussed for the case of identical dots.
