Measurement of the optical parameters of the Virgo interferometer.

The Virgo interferometer, aimed at detecting gravitational waves, is now in a commissioning phase. Measurements of its optical properties are needed for the understanding of the instrument. We present the techniques developed for the measurement of the optical parameters of Virgo.

Tomographic characterization of OPO sources close to threshold.

Pattern function quantum homodyne tomography (QHT) has been used for characterizing the output of a degenerate below-threshold type-I OPO. The recovered photon number distributions deviated from those relative to Gaussian thermal states. The Kurtosis of the homodyne data confirmed these deviations, thus proving the power of QHT to highlight unexpected features of quantum states.