Interferometric measurements and data analysis for the study of thermal noise in solids

Thermal noise constitutes a fundamental limitation to sensitivity in high precision experiments. While well understood at thermodynamic equilibrium, it has not been properly modeled in non-equilibrium conditions yet. We aim at investigating this regime experimentally using a macroscopic aluminum oscillator, consisting of a suspended rod with a cubic mass at the end. As a preliminary step, we focus on the thermal noise characterization under equilibrium conditions. In this thesis, using a quadrature phase differential interferometer, we investigate the longitudinal mode of the oscillator. By acquiring and analyzing the interferometric output in thermodynamic equilibrium, we aim to measure thermal noise in accordance with the fluctuation-dissipation theorem, with the future goal of studying its behavior outside thermodynamic equilibrium.