The Study Of Applications Of Cluster State In Quantum Information

Quantum information theory, which is one of the newest combination subject that brings together disciplines of quantum mechanics and information science, now is the hot research field of physics and information science. 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 quantum physics way. Nowadays, the quantum information processing and quantum communication is theoretically under intense investigation. We also make some studies in these fields, such as the entanglement of quantum state, quantum teleportation; quantum secure direct communication. we propose a scheme to implement the state propagation by using linear cluster state, and the other scheme to implement quantum secure direct communication with cluster state, they are of great importance to quantum information processing and quantum communication.The thesis consists of five chapters. In the first chapter, we introduce the history of development and latest progress in the field of quantum information.The second chapter studies the basic theories of quantum bit, quantum logic gate, quantum entanglement, quantum measurement, etc.The third chapter introduces quantum teleportation; studies some basic properties of cluster state, for example, it is maximally connected and the persistency of the cluster state is equal to their Schmidt measure; and proposes a scheme to implement the state propagation by using cluster state.The fourth chapter introduces quantum no-cloning theorem, quantum key distribution theorem and a representative kind of quantum secure communication: the "ping-pong " protocol. Different from key distribution whose object is to establish a common random key between two parties, a secure direct communication is to communicate secret messages directly without first establishing a random key to encrypt them. and introduces detailedly our quantum secure direct communication scheme based on cluster state. The scheme is based on 1D linear cluster states, using some unitary operations and suitable measurements to perform quantum communication, and its security is also analyzed, the error rate introduced by an eavesdropper who takes intercept-resend attack can be risen up to 43.75%.The fourth section of the third chapter and the fifth section of the fourth chapter are inivations of the thesis.In the fifth chapter, we give a concise summary of the thesis and make an expectation of the future in this research field.