  It is demonstrated a two-photon interfering technique based on
polarization-resolved measurements for the simultaneous estimation with the
maximum sensitivity achievable in nature of multiple parameters associated with
the polarization state of two interfering photonic qubits. This estimation is
done by exploiting a novel interferometry technique based on
polarization-resolved two-photon interference. We show the experimental
feasibility and accuracy of this technique even when a limited number of
sampling measurements is employed. This work is relevant for the development of
quantum technologies with photonic qubits and sheds light on the physics at the
interface between multiphoton interference, boson sampling, multi-parameter
quantum sensing and quantum information processing.
