Implementations For Quantum Remote State Preparation And Logic Gates

Quantum information is an interesting new science deriving from 1980s, it is one subject of combinations of quantum mechanics and information science. At present, quantum information is being developed so rapidly, and people had put forward plenty of significant theories, and make some great improvements in correlative experiments. There are two basic concepts in quantum information science:quantum logic gate operations and entanglement, where, logic gates describe evolutive and unitary operators of quantum states. Quantum computation process is regarded as a process that a series of basic quantum gates operations act on a standard initial state, and then some standard measurements are made. That is to say, quantum gate is a fundamental unit of quantum computation. As well as we know, entanglement states play an extremely important role in quantum-information processing. It can be used for proving various theories of quantum mechanics, and is a core resource in quantum-information processing. Quantum entanglement has lots of important applications, such as quantum teleportation, quantum remote state preparation, quantum telecloning, and so on. Due to their importance in quantum-information processing, quantum logic gates and quantum entanglement attract much attention. The exploring objects of our thesis are just the implementations for quantum logic gates and remote state preparation. This thesis is divided into seven chapters, where the fourth, fifth and sixth chapters are our works, and its framework is as follows:In the first chapter, we will introduce our exploring work and its background, concisely depict the derivation and development of quantum information, and present the main contents of this dissertation and arrangements for the whole text.In the second chapter, we will introduce some fundamental concepts and principal theories, which contain quantum bit (qubit), quantum non-cloning theorem, quantum unitary operations, projective measurement, and subsequently summarize the concepts of quantum information, quantum parallel computation and quantum communication.In the third chapter, we stress the concept, judgement, classification and scale of quantum entanglement. Besides, some important applications are reviewed, which include quantum teleportation, remote state preparation, quantum telecloning, quantum dense coding and so on.In the fourth chapter, one of theoretical schemes proposed by us is shown, i.e., remote implementation of multi-qubit quantum phase gates. In addition, we discuss the speciality of our scheme, and make some important comparisons between the other schemes and ours.In the fifth chapter, we demonstrate a scheme for remote preparation of an arbitrary two-qubit pure state via non-maximally entangled states and positive operator-valued measurement (POVM). In this chapter, we give the analysis of the experimental feasibility of our protocol; moreover, we make some discussions and comparisons on the particularity of our protocol.In the sixth chapter, we amply describe our scheme for remotely preparing single-and two-particle states in a four-level system. With the help of maximally entangled states and classical communication, one can achieve probabilistic remote state preparation (RSP). Moreover, the particularity and experimental feasibility of our schemes are discussed deeply.Finally, we make a summary of this thesis, and put forward the prospect for exploring work in the future.