  We discuss a cavity-QED scheme to deterministically generate entangled
photons pairs by using a three-level atom successively coupled to two single
longitudinal mode high-Q cavities presenting polarization degeneracy. The first
cavity is prepared in a well defined Fock state with two photons with opposite
circular polarizations while the second cavity remains in the vacuum state. A
half-of-a-resonant Rabi oscillation in each cavity transfers one photon from
the first to the second cavity, leaving the photons entangled in their
polarization degree of freedom. The feasibility of this implementation and some
practical considerations are discussed for both, microwave and optical regimes.
In particular, Monte Carlo wave function simulations have been performed with
state-of-the-art parameter values to evaluate the success probability of the
cavity-QED source in producing entangled photon pairs as well as its
entanglement capability.
