Efficient Quantum State Estimation with Over-complete Tomography
  It is widely accepted that the selection of measurement bases can affect the efficiency of quantum state estimation methods, precision of estimating an unknown state can be improved significantly by simply introduce a set of symmetrical measurement bases. Here we compare the efficiencies of estimations with different numbers of measurement bases by numerical simulation and experiment in optical system. The advantages of using a complete set of symmetrical measurement bases are illustrated more clearly. 
Chi Zhang, Guo-Yong Xiang, Yong-Sheng Zhang, Chuan-Feng Li and   Guang-Can Guo
quant-ph