  The method of quantum cloning is divided into two main categories:
approximate and probabilistic quantum cloning. The former method is used to
approximate an unknown quantum state deterministically, and the latter can be
used to faithfully copy the state probabilistically. So far, many approximate
cloning machines have been experimentally demonstrated, but probabilistic
cloning remains an experimental challenge, as it requires more complicated
networks and a higher level of precision control. In this work, we designed an
efficient quantum network with a limited amount of resources, and performed the
first experimental demonstration of probabilistic quantum cloning in an NMR
quantum computer. In our experiment, the optimal cloning efficiency proposed by
Duan and Guo [Phys. Rev. Lett. \textbf{80}, 4999 (1998)] is achieved.
