Quantum State Tomography: 'the best' is the enemy of 'good enough'
  In this paper, we examine a variety of strategies for numerical quantum-state estimation from data of the sort commonly measured in experiments involving quantum state tomography. We find that, in some important circumstances, an elaborate and time-consuming numerical optimization to obtain 'the best' density matrix corresponding to a given data set is not necessary, and that cruder, faster numerical techniques may well be 'good enough'. 
Max S. Kaznady, Daniel F. V. James