6. Conclusion

This chapter leads to the fundamental aspects of quantum correlations: entanglement and quantumness of correlations. The purpose of this chapter is to demonstrate that quantumness of correlations plays an important role in entanglement resource theory and by consequence in quantum information theory. It was presented that entanglement and quantumness of correlations connect each other in two different pictures. The relation derived by Koashi and Winter demonstrates the balance between quantumness of correlations and entanglement in the purification process. This balance leads to a formal proof for the irreversibility of the entanglement distillation protocol, in terms of quantumness of correlations. Indeed in this fashion quantumness of correlations revealed to play the main role in the state merging protocol, quantifying the amount of entanglement consumed during the protocol. In the named activation protocol, the quantumness of correlations of a given composed system can be converted into distillable entanglement with a measurement apparatus during the local measurement process. In resume, the entanglement created by the interaction between the system and the measurement apparatus is limited below by the amount of quantumness of correlations of the system.
