On mixed states entanglement and quantum communication: Aspects of quantum channels theory

Basic aspects of quantum communication based on quantum channels theory are reviewed together with suitable examples. The key notion of quantum channel capacity is discussed. The role of mixed states entanglement as a practical tool in quantum channels theory is explained in detail. Application of recent results on non-positive partial transpose bound entanglement conjecture to binding entanglement channels shows that validity of the conjecture for some states implies nonadditivity of two-way quantum channel capacity. Some aspects of robustness of entanglement in context of positive maps theory are also discussed.