Optimality of generalized Choi maps in M 3

Abstract A family of linear positive maps in the algebra of 3 × 3 complex matrices proposed recently by Bera et al 2024 Linear and Multilinear Algebra 1–16) is further analyzed. It provides a generalization of a seminal Choi nondecomposable extremal map in M 3 . We investigate when generalized Choi maps are optimal, i.e. cannot be represented as a sum of positive and completely positive maps. This property is weaker than extremality, however, it turns out that it plays a key role in detecting quantum entanglement.