Effective generation of polarization-entangled photon pairs in a cavity-QED system

We propose a cavity-QED scheme to effectively generate Einstein-Podolsky-Rosen polarization-entangled photon pairs. Assisted by a classical π-polarized pump field, a tripod four-level atom successively couples to two high-Q optical cavities possessing polarization degeneracy. Through stimulated Raman adiabatic passage process the polarization-entangled photon pairs can be produced.