Principles And Optical Realizations Of Quantum Information Processing

With the development of information technique and quantum mechanics, a new subject based on the law of quantum mechanics-quantum information theory comes into being. Because of the large improvements in computational efficiency and communication security by exploiting the superposition principle and the non-classical correlation of quantum mechanics, quantum information theory soon attracts much attention and becomes the hottest areas of modern academe. It is the quantum coherence which lies at the heart of quantum information that makes the manipulation of information-carrier qubits possible, and the occurrence of the information coding, storing and transferring in a unconventionality way. Nowadays the processing of quantum information is theoretically under intense investigation, people are eagerly to find physical system to testify potential improvements offered by quantum mechanics to the manipulation and the transmission of information. Based on the substantial development in quantum engineering and measurement of light in the past decades, quantum optical systems are ideal for the experimental test of the foundation of quantum mechanics as well as for the experimental implementation of quantum information processing.This thesis investigates the generation and preparation of several typical entangled states, the measurement and transmission of entanglement, as well as the typical information processing based on entanglement which includes quantum teleportation, quantum game and error-free discriminations of quantum states. Our mainly work is as follow:(1) Based on the representation of multiple qubits by single photon, we present a linear optical implementation for quantum teleportation of an unknown two-qubit entangled state by using linear optical elements. The optical elements used here are beam splitters, phase shifters and wave plates. In this optical proposal, five qubits are involved, one of them are built by the polarization of single photon, which is called the polarization qubit, and the others are constructed by the paths where the single photon takes, which is called the location qubit.(2) Present a proposal for optically implementing the quantum game of the two-player quantum prisoner's dilemma by using some linear and nonlinear optical elements. Further we present a feasible scheme by only using linear optical elements. The most important part of quantum Prisoner's dilemma is player's strategies and the gate which introduces entanglement. The strategies of each player are made up of two beam splitters and four phase shifters, and the entangling gate is consist of beam splitters, phase shifters and additional cross Kerr medium. In the further scheme of quantum prisoner's dilemma, in addition to beam splitters and phase shifters, the quarter-wave plates and half-wave plates are used to realize the strategies and the entangling gate.(3) Give an optical method for optimal error-free discrimination of some linear independent states by the coupling of the original particle to an ancillary system. The two systems are represented by different degrees of freedom of a single photon, one is the photon' s polarization, and the other is the photon' s travelling paths. The apparatus we used here are polarized beam splitters, wave plates and single photon detectors.(4) Propose a method for optically creating entangled squeezed vacuum states (SVSs) by introducing a SVS-phase shifter whose possible realization is...