  We study the time evolution of entanglement created by local or extended
excitations upon the ground state of a free-fermion chain. A single particle or
hole excitation produces a single bit of excess entropy for large times and
subsystem lengths. In case of a double hole, some of the coherence between the
excitations is preserved and the excess entropy becomes additive only for large
hole separations. In contrast, the coherence is always lost for particle-hole
excitations. Multiple hole excitations on a completely filled chain are also
investigated. We find that for an extended contiguous hole the excess entropy
scales logarithmically with the size, whereas the increase is linear for finite
separations between the holes.
