  Debugging quantum states transformations is an important task of modern
quantum computing. The use of quantum tomography for these purposes
significantly expands the range of possibilities. However, the presence of
preparation and measurement errors complicates the practical use of this
procedure. In this work, we investigate the possibility of estimating these
errors from experiment. These estimates are subsequently used to build a robust
quantum tomography model. The model allows one to accurately reconstruct
unitary errors of single-qubit gates. We show that, having such imperfect
single-qubit gates with pre-estimated errors, one can obtain transformations
close to ideal ones. A similar approach can also significantly mitigate
single-qubit gates cross-talk.
