We present a physical scheme for entanglement concentration of unknown atomic entangled states via cavity decay. In the scheme, the atomic state is used as a stationary qubit and the photonic state as a flying qubit, and a close maximally entangled state can be obtained from pairs of partially entangled states probabilistically.
We present a physical scheme for entanglement concentration of unknown atomic entangled states via cavity decay.In the scheme,each of the atoms is a three-level system,which has two ground states(|g〉,|e〉),and an excited state(|r〉),the atomic state is used as stationary qubit and photonic state as flying qubit.There are two nonmaximally entangled atom-pairs,one atom of every atom-pairs are capped in two leaked cavity,respectively.In the case of large detuning and the upper level |r〉 can be decoupled from the evolution during the interaction,applying classical laser pulses on the capped atoms and by detecting the photons leaked from the cavities,a close maximally entangled state can be obtained from the two pairs of partially atomic entangled states probabilistically.Our scheme is practical and the remote entangled states concentration via high quality fiber will be convenient.
Based on the interference effect of polarized photons, we propose a practical scheme for entanglement concentration of unknown atomic entangled states. In the scheme, two λλ-type atoms belonging to different entangled pairs are individually trapped in two spatially separated cavities. By the subsequent detection of the polarized photons leaking out of the separate optical cavities, Alice and Bob as two distant parties can probabilistically extract one maximally entangled four-atom Greenberger–Horne–Zeilinger (GHZ) state from two identical partially entangled Einstein–Podolsky–Rosen (EPR) pairs. We also discuss the influence of cavity decay on the success probability of the scheme. The scheme is feasible and within the reach of current experimental technology.