In this seminar we will present an analog model for lightcone fluctuations based on nonlinear quantum optical systems that has been studied recently in the literature. The key ingredient in this model is that a fluctuating background electric field can change the phase velocity of a probe field coupled to this background through the nonlinearities of the medium. These works consider nonlinear materials having a second order electrical susceptibility, and the background electric field prepared in both the vacuum state and the squeezed vacuum state. Here we will present a suitable generalization of these results and consider materials having susceptibility up to third order. This is important if one wishes to perform measurements using centrosymmetric materials like silicon, in which the second order susceptibility vanishes. We will also consider the background field prepared in a more general coherent squeezed state. In order to study vacuum flutuations, we propose a faithful test function to perform the calculation in contrast with the Lorentzian distribution used before. We argue that with a more realistic test function, the vacuum contributions to the lightcone flutuations are up to 100 times greater than the ones found before.
