The efficiency of quantum state tomography is discussed from the point of view of quantum parameter estimation theory, in which the trace of the weighted covariance is to be minimized. It is shown that tomography is optimal only when a special weight is adopted.
@article{arxiv.1010.3813,
title = {Efficiency of quantum state tomography for qubits},
author = {Koichi Yamagata},
journal= {arXiv preprint arXiv:1010.3813},
year = {2015}
}