Time-domain squeezing and quantum distributions in the pulsed regime

We investigate time-dependent properties of Einstein-Podolsky-Rosen (EPR) light beams generated in a nondegenerate optical parametric oscillator (NOPO) driven by a sequence of laser pulses with Gaussian time-dependent envelopes. This investigation continues our previous analysis [ H. H. Adamyan and G. Yu. Kryuchkyan Phys. Rev. A 74 023810 (2006)] and involves problems of two-mode quadrature squeezing as well as intensity-difference squeezing in the time domain. The peculiarities of EPR beams are also discussed in the framework of phase-space quantum distributions. Two kinds of non-Gaussian Wigner functions, for the reduced one-mode state of periodically pulsed NOPO and for EPR beams which are combined on a one-half beam splitter are calculated numerically. We also investigate the Wigner functions of intensity-correlated twin beams following the conditional photon state-preparation scheme. It is demonstrated that the Wigner functions involve negative values in parts of the phase space for the schemes with one, two, and three photons.