Quantum information processing using coherent states in cavity QED

Using the highly detuned interaction between three-level Λ-type atoms and coherent optical fields, we can realize the C-NOT gates from atoms to atoms, optical fields to optical fields, atoms to optical fields and optical fields to atoms. Based on the realization of the C-NOT gates we propose an entanglement purification scheme for mixed entangled states of coherent optical fields. The feasibility of the scheme has also been discussed at the end of the article.