Measuring the quantum state of light

We analyse several schemes for measuring the quantum state of a single light mode. These schemes are useful for experimentalists to gain the maximum information about non-classical light fields which they investigate. Measured or reconstructed from measurements are quasiprobability distributions for quadrature components. We address beam splitting, amplification and heterodyning as experimental schemes for measuring the Q function. We show that the squared Wigner function can be directly measured as a probability distribution. We analyse Optical Homodyne Tomography where the Wigner function is reconstructed from measured quadrature distributions. Finally, we discuss the influence of detection inefficiencies on the measured or reconstructed quasiprobability distributions. We show how this influence can be reduced.