Bipartite entanglement of quantum states in a pair basis (original) (raw)

Even if entanglement is a fundamental tool for quantum technologies, its non ambiguous detection and quantification is still limited to low dimensions or specific classes of states. In this sense every extension beyond such special cases is of the utmost importance. Here, we consider quantum states in arbitrary d × d dimensions, particularly relevant to quantum optics, written in terms of a pair basis where each state in the subsystem A is paired with only one state in B. We extend the class of states for which negativity is a necessary and sufficient measure of entanglement to mixtures of states in a pair basis. In addition, we provide analytical expressions for a tight lower-bound estimation of the entanglement of formation, a central quantity for quantum information applications. PACS numbers: 03.67.Mn, 03.65.Ud, 42.65.Lm