Entanglement Concentration For The Cluster State

In recent years, quantum information technology has gained great development, which is entering in experiment from theory stage, toward the practical direction. The construction of quantum computer with the huge parallel computing ability has become possible. Absolutely secure quantum communication system based on the physical properties of quantum states also is no longer a unreachable dream. Quantum information processing technology is more and more close to our actual application.Cluster state plays a vital role in the field of quantum information, especially in the one-way quantum computation. The research about the cluster state is very necessary. However, the cluster state will occur decoherence when it suffers from the environment noise. Entanglement concentration is one of the effective means to deal with the system decoherence effects caused by the environment noise, which has also gained wide attention. In this paper we will describe three typical cluster state concentration schemes. Actually, the previous three schemes formed the my research foundation about entanglement concentration of the cluster state.Subsequently, we proposed three improved schemes based on the three concentrated solutions.In the first two schemes, we finished the concentration of an arbitrary four-particle cluster state based on the photon. The first one of the schemes based on the photon, can be divided into two steps. In the first step a pair of particles need to be used as the auxiliary. The second step requires a single particle. In the second scheme, we realized a concentration protocol assisted with single photons based on the cross-Kerr non-linearity. The whole concentration scheme can be divided into three steps, and we will prepare an auxiliary single photon in every step. In addition, in the concentration process, we don’t need the quantum gates which are too difficult to achieve with the current technology, but the quantum non-demolition measurement and the conventional photons detectors. Moreover, we can get higher success probability with the help of circulation concentration. All of that makes our protocols more feasible and economic. Due to the electron is one of the candidate carriers to realize the quantum computer eventually. Entanglement decoherence is also one of the difficulties needed to be overcome for quantum computation. We research the entanglement concentration for the cluster state in the electronic system, and propose the concentration scheme for the cluster state based on charge detectors.