alpha-logarithmic negativity


© 2020 American Physical Society. The logarithmic negativity of a bipartite quantum state is a widely employed entanglement measure in quantum information theory due to the fact that it is easy to compute and serves as an upper bound on distillable entanglement. More recently, the $ąppa$ entanglement of a bipartite state was shown to be an entanglement measure that is both easily computable and has a precise information-theoretic meaning, being equal to the exact entanglement cost of a bipartite quantum state when the free operations are those that completely preserve the positivity of the partial transpose [Xin Wang and Mark M. Wilde, Phys. Rev. Lett. 125, 040502 (2020)PRLTAO0031-900710.1103/PhysRevLett.125.040502]. In this paper, we provide a nontrivial link between these two entanglement measures by showing that they are the extremes of an ordered family of $α$-logarithmic negativity entanglement measures, each of which is identified by a parameter $α$?1,∞. In this family, the original logarithmic negativity is recovered as the smallest with $α$=1, and the $p̨pa$ entanglement is recovered as the largest with $α$=∞. We prove that the $α$-logarithmic negativity satisfies the following properties: entanglement monotone, normalization, faithfulness, and subadditivity. We also prove that it is neither convex nor monogamous. Finally, we define the $α$-logarithmic negativity of a quantum channel as a generalization of the notion for quantum states, and we show how to generalize many of the concepts to arbitrary resource theories.

Physical Review A