The Probabilistic Cloning Of A Pair Of Orthogonal States

Quantum information based on quantum mechanics and information science is across-discipline which including several subjects. It includes two aspects, quantumcomputation and quantum communication. In recent twenty years, both in the theory andexperiment, there are great achievements on quantum information, especially in quantumcommunication. Meantime, compared with the classical computers, quantum computers haveadvantages for solving some particular problems, so it attracts more and more attention ofscientists.Quantum No-cloning theorem is an important content of the quantum information.No-cloning theorem proposed by Wootters and Zurek prevents accurately cloning of anyunknown quantum states.However, one can consider the approximate cloning of the states,First, Buzek and Hillery present the optimal quantum cloning machine. Then Duan and Guopropose probabilistic quantum cloning machine. In this paper, we use the probabilisticquantum cloning machine to clone a pair of nonorthogonal states and realize this cloningprocess in theory by suitable universal logic gates.In the first chapter, we introduce the basic knowledge of quantum information, includingquantum bit, logical quantum gate, unitary matrix and universal logic gates.In the second chapter, we give the quantum no-cloning theorem. Then we describe theuniversal quantum copying machine and the probabilistic quantum cloning machine.In the third chapter, we find out a unitary matrix based on the probabilistic quantumcloning machine proposed by Duan and Guo. Then we decompose it into a product ofmultiple two-level unitary matrices and realize it by suitable universal logic gates.