Wen-Hai Zhang
Huainan Normal University, Huainan, China

Series: Physics Research and Technology
BISAC: SCI055000

The linearity and the superposition principle in quantum mechanics lead to the no-cloning theorem that confirms the impossibility of perfectly cloning an arbitrary unknown quantum state. In this chapter we review the quantum cloning process, following the taxonomy of the quantum systems to be cloned. In a transparent understanding fashion and the rigorous demonstrations we mainly concentrate on the quantum cloning transformations by which the quantum cloning machines can be qualified as optimal ones in term of the fidelity of the clones. In particular, for the purpose of the didactic examples, the mature researches of the pure quantum state cloning, such as the universal quantum cloning, the phase-covariant cloning and the real state quantum cloning, as well as the coherent state cloning, are focused. In addition, the recent study of the probabilistic quantum cloning with its applications is discussed. (Imprint: Nova)