Geometry of entanglement witnesses parameterized by SO(3) group
  We characterize a set of positive maps in matrix algebra of 4x4 complex matrices. Equivalently, we provide a subset of entanglement witnesses parameterized by the rotation group SO(3). Interestingly, these maps/witnesses define two intersecting convex cones in the 3-dimensional parameter space. The existence of two cones is related to the topological structure of the underlying orthogonal group. We perform detailed analysis of the corresponding geometric structure. 
Dariusz Chru\'sci\'nski, Filip A. Wudarski
quant-ph math-ph math.MP