| Quantum information is a subject that is a combination of physics science and information science, and is based on the basic theory of quantum mechanics. Quantum information includes quantum communication and quantum computation. For the wonderful character of quantum world, quantum information has some new characters compared with classical information.Quantum teleportation is an important part of quantum information. Its basic element is as following: in order to teleport an unknown quantum state, the information about protoplast is divided into classical information and quantum information. The receiver gains classical information by the sender measures protoplast and gains quantum information through the quantum channel. After the receiver gains these two kinds of information, he can make an ideal duplication about protoplast. That is to say, using quantum entanglement, the sender does not send any qubit but send an unknown quantum state, that is quantum teleportation.Since Bennett et al. proposed a scheme for teleporting an unknown quantum state of one-particle in 1993, various teleportation schemes have been proposed. In this paper, we propose a new scheme for teleporting an unknown quantum state of one-particle which is more efficient and economical compared with standard one-particle quantum teleportation, what's more, as an application of this scheme we proposed a quantum secure direct communication protocol.The decoherence may arise because of the interaction between quantum channel and environment. At that moment, quantum channel is always not a maximally entangled state. A scheme for probabilistic teleportation of two-particle state is showed by us when quantum channels are "genuine" four-qubit partially entangled states. Teleportation will be realized successfully with certain probability by unitary transformation and introducing an auxiliary particle. |
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