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 Bužek, Derka, and Massar [V. Bužek, et al., Phys. Rev. Lett. 82 (1999) 2207]. The estimation error asymptotically decreases to zero with an order of 1/n21/n2 at least.