Generation Of Multiparticle Entangled State

Quantum entanglement is a unique phenomenon of quantum physics. It is one of the most fancy and enigmatical characteristic for quantum physics differentiating from classical physics. In the field of quantum information, quantum entanglement acts as an important role and used widely as a significant resource in quantum teleportation, quantum dense coding, quantum key distribution, quantum computation, and so on. On the other hand, it opens an efficient way for people to deeper understand and do farther research on the essence of quantum mechanics, and also for the wide application of quantum theory. The multiparticle entangled states have more general construction and properties than two-particle entangled states which make it indispensable for the application of quantum information science. To explore fully quantum entanglement is vital for quantum theory, especially in the field of quantum information science. We focus our research on generation of the entangled states and the main results are as follows:1. We have presented a way to investigate how to generate the quantum cluster state, an important multiqubit entangled state in the measurement-based quantum information and quantum computing. Moreover, a multipartite entanglement analyzer is also proposed in it. On the other hand, we give a universal quantum computation scheme for free-electron in DFS. By this way free photons could be fully modelled with free electrons.2. A potential scheme is proposed for deterministically generating complete sets of GHZ state of entangled photons in the context of cavity quantum electrodynamics (QED). The scheme includes twice interactions of atoms with cavities, in which the first interaction is made in two-mode optical cavities and the second one exists in a microwave cavity. Then a certain measurement on the inner states of the atoms, we can get entangled photons. By this way the complete set of the entangled two- or more-photon states can be generated deterministically, and the implementation time remains constant with the increase of the size of the entangled photon states.3. Based on the physical system of cavity QED, we showed how to efficiently generate of the cluster states and W states with superconducting- quantum-interference-device qubits. We consider the cavity decay in our model and analytically demonstrate its detrimental influence on the prepared entangled states.4. We proposed a scheme for efficient and high-fidelity generation of four atomic Cluster state in one step with combining cavity-QED and linear optics, and we also showed how to extend to the case of more atoms. Otherwise, by combining cavity-QED and linear optics, a scheme for purification of entanglement of two atoms from not-too-impure entangled state by checking the parity of the two atoms through the cavity input-output process is also presented in another work.