Quantum Information Schemes Based On Quantum Entanglement

Quantum information theory is an inter-discipline of quantum mechanics and information theory, which is competent in some of impossible task within the conventional information science. Quantum communication is a way of effective information transmission using quantum state as information unit. It is an important and early researched branch of quantum information, including quantum teleportation, quantum cloning, quantum secret sharing, etc.Entanglement plays a more and more important role in the processing of dealling quantum information. Entanglement is a striking and unimaginable phenomenon because of its nonlocality allowed in quantum mechanics. In the field of quantum information, entanglement, which is a very useful information resource, plays a key role in quantum teleportation, quantum dense coding, quantum cryptography and quantum computation (speed up computation in quantum algorithms, correct-error and tolerant-error). Bipartite entangled states have been known very well by scientists and some of generation schemes have been proposed. However, multipartite or multiparticle entangled states, especial for multi-level entangled states, are still under research. In our thesis, we mainly propose some quantum information schemes based on the character of quantum entangled states, the results are following:1. Usually, positive measurement is necessary in quantum teleportation schemes, In this paper, based on the character of positive operator-valued measure, we successfully realize a scheme for probabilistic teleportation of an arbitrary unknown two-qubit state by using a proper positive operator-valued measure instead of usual projective measurement.2. A scheme, which includes a qutrit-state teleportation, for cloning an unknown single qutrit state with assistance by performing a single-qutrit measurement is realized. It is shown that, from the angle of the state preparer Victor, the present scheme can be simplified to be a remote state preparation scheme disregarding the teleportation proce.3. By studying hard quantum secret sharing, we generalize the two-dimensional quantum state sharing schemes to three-dimensional case successfully. Then we propose a three-party qutrit-state sharing scheme, and we also consider the multi-party case.