Phase-space interferences all the source of negative values of the Wigner distribution function

It is shown that the negative values of the Wigner distribution function in classical optics are a consequence of the phase-space interference among t he Gaussian beams into which an arbitrary light distribution (or a superpos ition of light distributions) can be decomposed. These elementary Gaussian beams partition the phase space in wave optics in adjacent, interacting, fi nite-area cells, in contrast to geometrical optics, where the phase space i s continuous and a light beam can be decomposed into a number of perfectly localized, noninteracting rays. (C) 2000 Optical Society of America [S0740- 3232(00)00112-5] OCIS codes: 070.0070, 070.4560, 100.0100, 100.2960.