Quantum Information Processing With The Degrees Of Freedom Of Photon Polarization And Electron Spin

With the rapid development of quantum information, a variety of physical sys-tems have came into being. The polarized photon which act as flying qubit in optical system capable could carry quantum information and is suitable for long-distance quantum communications; The free electron in electron system has charge and spin two degrees of freedom. The measurement of charge will not affect the electronic spin degree of freedom. In addition, the semiconductor quantum dot system in solid state system has the advantages of integratability and scalablity. Therefore, these two systems have already drawn much attention in quantum information processing tasks. In this dissertation, we mainly research the two systems for implementing quantum information processing tasks. The main contents are as follows.Based on the optical system, the concentration of multi-photon entanglement assisted by quantum nondemolition detection is presented. We have realized the concentration of Bell state, GHZ state, three-photon W state and multiphoton par-tially entanglement W state and calculated the success probability. In the present schemes, we use linear optical elements and quantum nondestructive detection in-stead of the tradition parity-check detector. Comparing with the other schemes of entanglement concentration, the present schemes have no need for auxiliary photon and the operation steps are simplified.Based on the electronic system, firstly, in the solid state electronic system, we use the system of quantum dot-single side optical cavity to realize a special CNOT gate which the parity state of two spin electrons could control the polarization state of the photons. Then we realize the optimal1â†'2universal, optimal1â†'2phase-covariant and optimal economical1â†'3phase-covariant quantum cloning machines. Subsequently, we realize a CNOT gate and Toffoli gate of electrons by using a quantum dot-bilateral optical cavity system. Based on these two logic gates, we realize the quantum cloning machine to copy a quantum state near a given state. Secondly, we propose the schemes for implementing hyperentangled Bell state analysis in free electron system, in which the sixteen hyperentangled Bell states can be distinguished without destroyed. Then we generated four-electron high entangled states, including the cluster state,|x> state, and symmetric Dicke state.