State reconstruction of a qutrit by a minimal set of discrete measurements

We propose a simple and practical method for measuring the parameters of a fully or partially coherent superposition state of a qutrit quantum system. The method is based on the coupling of the qutrit to an excited state by two polarized laser fields and measurement of the fluorescence or ionization signal from the excited state for a discrete set of laser ellipticities and phases. We show that nine independent signals suffice to determine the parameters of an arbitrary unknown mixed qutrit state.