Generation Of Multipartite Continuous-variable Entanglement Via Cavity Quantum Electrodynamics

Quantum entanglement is the basic resource in quantum communication and computa-tion. The generation of multipartite entanglement becomes an essential research of quantum information science and attracts many interests. This thesis considers several novel methods for generating scalable multipartite entangled states of light via cavity quantum electrody-namics, and describes applications of these methods to scalable quantum communication and computation.First, we propose a scalable scheme to prepare a class of multimode cluster entangled states. In terms of graph states, all modes are denoted by the nodes, and the lines connect-ing the nodes represent the interactions between the connected nodes. Our cluster entangled states correspond to two-colorable graphs, in which the nodes belong to two different fam-ilies, and the lines connect only the nodes of different families. The physical mechanism is attributed to quantum interference between multiple pathways for wave-mixing parametric interactions in near-resonant systems.Second, based on the newly constructed multipartite cluster states for continuum vari-ables [J. Phys. B44205504(2011)], we introduce a method to implement multi-mode squeezing operators. This scheme generates unitarily multi-mode field squeezing and clus-ter entangled states via cavity quantum electrodynamics(Cavity QED). This kind of squeeze field operators decoupled from the atomic degrees of freedom. The squeeze parameter are proportional to the number of atoms, and so they can be large. We show perfect squeezing and robust output entanglement can be achieved outside the cavity.Thirdly, it is known that one reservoir of driven two-level atoms can establish two-mode interactions and generate bipartite continuous-variable entangled light. Here we show that three-mode interactions can be created by combining two such reservoirs, each of which interacts with two adjacent fields in frequency. It is shown that the van Loock-Furusawa criteria [Phys. Rev. A67052315(2003)] are well satisfied for a wide range of the relevant parameters. This determines that tripartite continuous variable(CV) Greenberger-Horne-Zeilinger(GHZ) entanglement is obtainable. The conditions for the detunings needed to create entanglement in our scheme are given. The scalability to more fields is straight-forward, allowing an alternative implementation of a multipartite quantum networks with continuous variables. Together these proposals utilize cavity quantum electrodynamics to produce scalable CV cluster entangled states, the multi-mode squeezing operators, and scalable CV GHZ entanglement. The findings in our schemes may be potential resources for the future scalable quantum communication and computation.