Non-classical field characterization by high-frequency, time-domain quantum homodyne tomography

We report about the realization and the applications of an efficient pulsed optical homodyne apparatus operating in the time domain at the high repetition rates characteristic of commonly used mode-locked lasers for the analysis of quantum light states.We give a full characterization of our system by shot-noise measurements and by verifying its capability to work in a gated configuration at lower acquisition rates. We demonstrate the potential of this high-frequency time-domain detector by applying it to the reconstruction of the density matrix elements and of the Wigner functions of various field states by means of quantum tomography. Results are shown for the complete characterization of simple coherent states with low average photon number, of single-photon Fock states and of the so-called single-photon added coherent states, which result from the elementary excitation of a classical wave-like field.Wigner functions with negative values are observed for the non-classical states and an overall efficiency of about 60% is obtained for the generation/detection system.