  We propose a scheme that utilizes the collective enhancement of a photonic
mode inside an atomic ensemble together with a proper Zeeman manifold in order
to achieve a heralded polarization entangled Bell state. The entanglement is
between two photons that are separated in time and can be used as a post
selected deterministic source for applications such as quantum repeaters where
a subsequent entanglement swapping measurement is employed. We present a
detailed analysis of the practical limitation of the scheme.
