Parallel Treatment of Estimation of SU(2) and Phase Estimation
  We discuss the accuracy of the estimation of the $n$ identical unknown actions of $\SU(2)$ by using entanglement. This problem has a similar structure with the phase estimation problem, which was discussed by Bu\v{z}ek, Derka, and Massar\cite{BDM}. The estimation error asymptotically decreases to zero with an order of $\frac{1}{n^2}$ at least. 
Masahito Hayashi