Fig. 1
From: A mirrored pair of optimal non-decomposable entanglement witnesses for two qudits does exist
This graphic displays the set of bipartite states (green) together with convex subsets of PPT states (blue) and separable states (grey). States which are PPT but not separable are bound entangled. Entanglement witnesses \(W_i\) are represented by straight lines. In Ref.25 the conjecture was put forward based on the study of several known examples, that for a pair of mirrored EWs, \(\{W_1,W_2\}\) if \(W_1\) is optimal and non-decomposable then \(W_2\) is decomposable (or it’s not a witness at all). This paper shows that surprisingly pairs of mirrored optimal EWs exist, here \(\{W_3,W_4\}\) (dotted lines), which both detect PPT-entangled states.
