Linear maps preserving separability of pure states
  Linear maps preserving pure states of a quantum system of any dimension are characterized. This is then used to establish a structure theorem for linear maps that preserve separable pure states in multipartite systems. As an application, a characterization of separable pure state preserving affine maps is obtained. 
Jinchuan Hou and Xiaofei Qi
quant-ph math.FA math.OA