Quantum Teleportation Of States Of The Quantum Information

Quantum information science, which mainly includes quantum computer and quantum communication, has increasingly evolved as a new object. Because the carrier of information in this subject, all the problems related to information should be resolved by means of quantum theory. Therefore, quantum information science exhibits a number of advantages corresponding to classical counterpart. In the past few years, quantum information has made a surprise progress both in theoretical and experimental fields, it has created many miracles, such as absolute secure quantum teleportation, quantum key, quantum dense coding, and so on. Quantum information is an important branch of quantum information, which is greatly concerned by people currently.Quantum teleportation is one of the simplest method in quantum communication. And it is greatly important to help people know the secret regular of nature in physical field. The method that the information is transported by quantum states can complete mass of information to exchange simultaneously, and it is absolutely secrete. There are many advantages of quantum teleportation, dependability is high, safety is strong, resource is economized, and the complexity of communication is cut back. If the technology of quantum teleportation is realized, it will be applied in quantum computation and quantum communication. But, the international field of science supposes quantum network exchanging quantum information by phone (flying qubit) and store and deal quantum information by atom (stationary qubit). This field is lying in the stage of unit technological research; many key problems are imperatively waiting to answer. The main results of this thesis are as follows:1. Based on the proposal of Braunstein and Kimble (B-K), we study continuous variables quantum teleportation via minimum-correlation mixed state. The results show that the mixed entangled state as a generalized type of Einstein-Podolsky-Rosen (EPR) entangled states is a good quantum channel. As an example, we analyze in detail teleporting a coherent state by means of this channel. When the parameters of minimum-correlation mixed state are chosen properly, the fidelity nearly will reach to one. The minimum-correlation mixed state as a quantum channel is better than the two-mode squeezed vacuum state.2. Based on cavity QED, we proposed an experimental scheme of simultaneous communication of quantum network. And the schemes that three people and more simultaneously communicate are detailed discussion. In the scheme the atoms interact simultaneously with a highly detuned cavity mode with the assistance of a classical field. The scheme is insensitive to the cavity decay and the thermal field. Bell states can be exactly distinguished via detecting the atomic state, and the simultaneous communication of quantum network can be realized easily.