Fluctuations in High-Precision Experiments – Material Aspects, Modeling and Mitigation

Thermal fluctuations play a crucial role for the ultimate sensitivity of instruments in highprecision optical metrology such gravitational wave detectors or ultra-stable laser cavities. The fluctuations in these optical systems result from the complex interplay of dissipation processes and optical fields. Particularly critical is thermal noise, for instance caused by the thermally driven motion of the atoms in the solid. In this lecture we introduce relevant noise mechanisms and discuss their coupling to the readout of the experiments. We illustrate that by a deliberate spatial distribution of optical and mechanical fields the readout of thermal noise can be minimized. To this end, optical micro-and nanostructures are promising to outperform conventional multilayer based optics by several orders of magnitude. This lays the foundation for gravitational wave astronomy and laser spectroscopy with unprecedented precision.