Study of the cloning fidelities for the entanglement of a pair of quantum bits

The cloning fidelities is broadly investigated for the entanglement of a pair of quantum bits. Some new analytical descriptions of the cloning fidelities have been obtained for the entanglement of a pair of quantum bits, generalizing asymmetric cloning transformations and considering a special circumstance. We derive some intact mathematical expressions and simulation results, having the extensive physics meaning, for the investigation of the separability-preserving cloning machine that duplicates all entangled states of two qubits.