Non-Gaussianity of quantum fields during inflation

In this paper, we discuss how non-Gaussianity of cosmological perturbations arises from inflation. After introducing the in–in formalism to calculate the n-point correlation function of quantum fields, we present the computation of the bispectrum of the curvature perturbation generated in general single-field inflation models. The shapes of the bispectrum are compared with the local-type non-Gaussianity that arises from nonlinear dynamics on super-horizon scales.