We propose simple schemes for generating W-type multipartite entangled states in cavity quantum electrodynamics (CQED). Our schemes involve a largely detuned interaction of λ-type three-level atoms with a single-mode cavity field and a classical laser, and both the symmetric and asymmetric W states can be created in a single step. Our schemes are insensitive to both the cavity decay and atomic spontaneous emission. With the above system, we also propose a scheme for realizing quantum-information concentration which is the reverse process of qu...
