  We show that many-body correlations among excitons originating from the Pauli
exclusion principle in a quantum well embedded inside a microcavity provide a
possibility to produce pairs of entangled photons by ultrashort laser pulses
with a yield of $\sim 10^{-2}$. The quantum-field theoretical two-particle
density matrix in second quantization is used to calculate entanglement for
arbitrary emission angles. %At time scales where the heavy-light hole splitting
is resolved the resonances corresponding to different two-exciton %states
develop, which allow for a simple kinematic theory relating the %states of the
outgoing photons with the respective two-exciton states. Largest response can
be expected at symmetric emission angles for resonances with the heavy-heavy
and light-light two-exciton states with remarkably nontrivial dependence of
entanglement on the emission angles and on the ellipticity parameters of the
excitation. We show that the angle dependence can be tailored by means of the
microcavity. Interestingly, the emitted entangled 2-photon states are always in
a triplet state.
