Stochastic parametric modulation of linear and non-linear oscillators: Perturbation theory of the response function

We study a stochastically driven, damped nonlinear oscillator whose frequency is modulated by a white or coloured noise. Using diagrammatic perturbation theory, we find that in the absence of nonlinearity, parametric modulation by a coloured noise can lead to a Kapitza pendulum-like stabilization of an unstable configuration provided the noise is anti-correlated. Further, we show that for modulation by a white noise of amplitude $\lambda$ and correlation strength $F$, the system will have an extremely large response if the product of ${\lambda }^{2}F$ equals a specific combination of the frequency and the damping coefficient. This prediction can be experimentally tested.