Atomic entanglement concentration via photonic Faraday rotation in cavity QED

By utilizing Faraday rotation of photons, we present a highly efficient protocol for entanglement concentration of atomic Bell states, which departs from the conventional method of sequential interactions between the auxiliary photon and two optical cavities. Instead, the simultaneous interaction of the auxiliary photon with two atomic cavities is involved in order to significantly reduce the time requirement for achieving atomic Bell state entanglement concentration. By employing iterative applications of the protocol for entanglement concentration, the discarded states can be repeatedly concentrated, efficiently increasing the probability of success. Furthermore, our entanglement concentration protocols (ECPs) operate in low-Q cavities, which are easier to implement in practical applications than high-Q cavities. Finally, it can be generalized to an N-atom GHZ states entanglement concentration protocol.