Quantum correlations support probabilistic pure state cloning

• Involved quantum correlations in the optimal probabilistic scheme for cloning two states.
• Suitable unitary transformations remove the entanglement from some partitions.
• The quantum discord assists the partitions without entanglement.

The probabilistic scheme for making two copies of two nonorthogonal pure states requires two auxiliary systems, one for copying and one for attempting to project onto the suitable subspace. The process is performed by means of a unitary-reduction scheme which allows having a success probability of cloning different from zero. The scheme becomes optimal when the probability of success is maximized. In this case, a bipartite state remains as a free degree which does not affect the probability. We find bipartite states for which the unitarity does not introduce entanglement, but does introduce quantum discord between some involved subsystems.