On the structure of entanglement witnesses and new class of positive   indecomposable maps
  We construct a new class of positive indecomposable maps in the algebra of 'd x d' complex matrices. Each map is uniquely characterized by a cyclic bistochastic matrix. This class generalizes a Choi map for d=3. It provides a new reach family of indecomposable entanglement witnesses which define important tool for investigating quantum entanglement. 
Dariusz Chruscinski, Andrzej Kossakowski