Cloning Of Two-particle Entangled State And Deleting Of BB84 States

Quantum theory was a great discovery in science and technology of the twentieth century, which uncovers the laws that govern the action of microscopic world and shows that the world is governed quantum laws essentially and quantum laws are similar to classical laws in macroscopic world. The combination of quantum mechanics, information theory and computer science yields a new branch of science that is called quantum information theory in the eighties of the twentieth century. Quantum information theory can exceed the classical limitation of information theory in the aspects of increasing the speed of information computation, increasing the storage capacities of information and insuring information security etc. by making use of the striking features of quantum mechanics. It is hopeful to lead to a new revolution of information technology. In recent years in quantum information field great progress has been made in theory and on experiment. At present quantum information theory has been paid great attention by the scientific world, information industrial field and various countries' government as its great academic value and potential technology application. Quantum information theory includes quantum communication and quantum computation. Quantum communication includes quantum teleportation, quantum cryptography, and quantum cloning, and so on.Quantum cloning is an important component of quantum information and since 1996 year has been hot spot of quantum information field as its important application in the attack and defense of quantum key, and potential application in quantum state's measurement, estimation, reconstruction and in quantum computation. Some aspects of quantum cloning and quantum deleting are studied in this paper, the results are following:1) We have constructed a scheme that can probabilistically implement copies of an original state or orthogonal complement state of an unknown two-particleentangled state with the help of a state preparer in three different places.2) We propose a scheme that deleting one of two identical copies from BB84...