  Phase estimation is the most investigated protocol in quantum metrology, but
its performance is affected by the presence of noise, also in the form of
imperfect state preparation. Here we discuss how to address this scenario by
using a multiparameter approach, in which noise is associated to a parameter to
be measured at the same time as the phase. We present an experiment using
two-photon states, and apply our setup to investigating optical activity of
fructose solutions. Finally, we illustrate the scaling laws of the attainable
precisions with the number of photons in the probe state.
