Many transformations which can be achieved without error on classical bit cannot be perfectly implemented on qubit, the quantum analogue of a bit, i.e. the fidelities of these processes have an upper bound. The machines that reach these bounds are called optimal. Here we report an experimental realization of two of these devices: the universal-NOT gate and the optimal quantum cloning of N=1 input qubit into M=2 output qubits by a quantum-injected optical parametric amplifier.