  By adopting the concept of fidelity, we investigated efficiency of quantum
state transfer with the XX chain as the quantum channel. Different from the
previous works, we concentrated on effects of spin and magnetic impurity on
fidelity of quantum state transfer. Our results revealed that the spin impurity
cannot prevent one from implementing perfect transfer of an arbitrary one-qubit
pure state across the spin channel, however, the presence of magnetic impurity
or both spin and magnetic impurities may destroy the otherwise perfect spin
channels.
