Confrontation between noise and dielectric measurements on a liquid crystal in the paraelectric SA andferroelectric SC phases

Dielectric and noise measurements versus frequency have been performed on a liquid crystal in the paraelectric SA and ferroelectric $S^*_{\rm C}$ phases. A confrontation of these measurements is presented on the basis of the fluctuation-dissipation theorem which shows that these techniques both give similar results linked to the observation of the classical soft mode and Goldstone mode in the SA and $S^*_{\rm C}$ phases respectively.