Probability Of The General State Of Two-level Two-particle And Single-particle S Level Quantum State Transfer

Quantum information is a new subject that is combination of information science and quantum theory. Quantum teleportation allows transmit an unknown quantum state from a sender, traditionally named Alice, to receiver, or Bob, both are spatially separated. Moreover, it may have applications in quantum dense coding and quantum cryptography. In 1993, Bennett et al proposed a scheme for teleporting an unknown quantum state of one-particle. Since then, quantum teleportation has developed rapidly. At present, it has been generalized to many cases.The principles of quantum teleportation: the information of original can be divided into classical information and quantum information. Classical information is obtained by measuring original. Quantum information is other information which sender cannot obtain by measurement. Receiver can produce exact replica of original after he receiver two kinds of information. In this course, original does not be sent to receiver. Only quantum state of original will be sent. Sender can even know nothing of this quantum state. Because classical information is indispensable to quantum teleportation and the transport speed of classical information does not exceed velocity of light, quantum teleportation does not violate quantum no-cloning theorem and principle of relativity.On the basis of principles of quantum teleportation, work that has been done in this thesis is as following:In practice, the entangled state used as quantum channel is always not a maximally entangled state because of interference of environment. By using partly entangled pure state, we present a scheme of probabilistic teleportation. In this scheme unitary transformation and local measurement take the place of Bell state measurement, and then proper unitary transformation and the measurement on an auxiliary qubit with the aid of classical communication are performed. In chapter II, A scheme for probabilistic teleporting unknown quantum pure state of two 2-level particles state of general formation by partly pure entangled four-particle states is proposed. In chapter III, A scheme for probabilistic teleporting an unknown one-particle state of S-level by a group of partly pure entangled two-particle states is proposed.