Interpolating between Positive and Completely Positive Maps: A New Hierarchy of Entangled States

Entropy (Basel). 2021 May 18;23(5):625. doi: 10.3390/e23050625.

Abstract

A new class of positive maps is introduced. It interpolates between positive and completely positive maps. It is shown that this class gives rise to a new characterization of entangled states. Additionally, it provides a refinement of the well-known classes of entangled states characterized in terms of the Schmidt number. The analysis is illustrated with examples of qubit maps.

Keywords: Schmidt number; Schwarz inequality; contractivity; positive maps; qubit maps.