  We report on a scheme for the creation of time-bin entangled states out of
two subsequent single photons. Both photons arrive on the same input port of a
beamsplitter and the situation in which the photons leave the beamsplitter on
different output ports is post-selected. We derive a full quantum mechanical
analysis of such time-bin entanglement for emitters subject to uncorrelated
dephasing processes and apply this model to sequential single photons emerging
from a single semiconductor quantum dot. Our results indicate that the
visibility of entanglement is degraded by decoherence effects in the quantum
dot, but can be restored by use of CQED effects, namely the Purcell effect.
