Realizing probabilistic identification and cloning of quantum states via universal quantum logic gates - art. no. 062310

Probabilistic quantum cloning and identifying machines can be constructed v ia unitary-reduction processes [Duan and Guo, Phys. Rev. Lett. 80, 4999 (19 98)]. Given the cloning (identifying) probabilities, we derive an explicit representation of the unitary evolution and corresponding Hamiltonian to re alize probabilistic cloning (identification). The logic networks are obtain ed by decomposing the unitary representation into universal quantum logic o perations. The robustness of the networks is also discussed. Our method is suitable for a k-partite system, such as quantum computer. and may be gener alized to general state-dependent cloning and identification.