Generation of gaussian entangled states of light in an array of nonlinear waveguides

Abstract: We investigate the process of entangled state of light generation while propagation along a one dimensional array of single-mode nonlinear waveguides. We consider a situation when entanglement is formed due to spontaneous parametric down-conversion of the pump which is present only in a signal waveguide. In the considered process the generated state of light is multi-mode squeezed. We demonstrate that starting from certain distance of light propagation only pairs of waveguides, located symmetrically with respect to the pumped one, occur to be entangled. Also there is an optimal pump amplitude for which the formed quantum correlations are most pronounced. Entanglement for multi-mode squeezed states may be very sensitive for phase fluctuations in the pump. We investigate the influence of such noise on the discussed process. We demonstrate that for situation of generation of few photon entangled states the influence of phase fluctuations is negligible. But it dramatically increase with the growth of average photon numbers in the formed quantum states.