Sparse anisotropic positive maps for qutrit entanglement: exact indecomposability and PPT geometry
The paper introduces an exactly solvable family of sparse positive maps on qutrits controlled by two parameters, w and z. It precisely maps out regions for positivity, complete positivity, and decomposability. It establishes that indecomposability is linked to PPT entanglement and analyzes the geometry of associated edge states at a specific point.