| Quantum information is a cross subject of quantum mechanics and informationscience. The application of quantum mechanics is used for informatics, it brings newdevelopment prospect. The concept of quantum entanglement of quantum mechanicsplays a vital role in quantum computation and quantum communication fields.The main entangled states of quantum mechanics include Bell states, GHZstates, W states and clusters states, etc. Different entangled states have differentcharacteristics. And different entangled states with different preparation methods havedifferent usages. The research of entangled states became the focus of attention ofquantum mechanics. Clusters states have maximally connected and persistency ofentanglement. Using clusters state for quantum communication is theoreticallysuperior to other entangled states.According to the correlation of quantum entanglement and nocloning theorem,many quantum key distribution schemes and quantum teleportation schemes that usedifferent entangled states for quantum communication, are proposed. The mostimportant advantage of quantum information is that the information process isunconditional security.In the paper, a quantum key distribution scheme based on cluster states isproposed. The sender and the receiver get the key and detect the security with Bellmeasurement. In this method the clusters are distributed as quantum keys. Then thispaper proposes another secure communication scheme, quantum secure directcommunication scheme. There are two schemes that base on the four-qubit clusterstates or five-qubit cluster states in the fourth chapter. In the scheme these clusterstates are used to transmit information as quantum channel. At first, receiver andsender need to establish secure quantum channel, after that they can complete secrecycommunication. |
