Iterative algorithm for reconstruction of entangled states
  An iterative algorithm for the reconstruction of an unknown quantum state from the results of incompatible measurements is proposed. It consists of Expectation-Maximization step followed by a unitary transformation of the eigenbasis of the density matrix. The procedure has been applied to the reconstruction of the entangled pair of photons. 
J. Rehacek, Z. Hradil, and M. Jezek