  Probabilistic quantum cloning and identifying machines can be constructed via
unitary-reduction processes [Duan and Guo, Phys. Rev. Lett. 80, 4999 (1998)].
Given the cloning (identifying) probabilities, we derive an explicit
representation of the unitary evolution and corresponding Hamiltonian to
realize probabilistic cloning (identification). The logic networks are obtained
by decomposing the unitary representation into universal quantum logic
operations. The robustness of the networks is also discussed. Our method is
suitable for a $k$-partite system, such as quantum computer, and may be
generalized to general state-dependent cloning and identification.
