Capturing Gravitational Waves in a World of Noise

The detection of gravitational waves has transformed our understanding of the Universe, providing new insights into massive astrophysical events such as black hole mergers and neutron star collisions. This thesis addresses the key challenges involved in detecting these extremely weak signals, focusing on advanced noise reduction techniques and control systems that enhance detector sensitivity. Gravitational-wave detection is achieved using interferometric detectors like LIGO, Virgo, and KAGRA, which measure infinitesimal distortions in space-time. However, these detectors face limitations from various noise sources, including seismic, thermal, quantum and particularly technical noise. This work presents the development and implementation of a Multiple-Input Multiple-Output (MIMO) control system for the Advanced Virgo Plus detector, improving sensitivity by decoupling noise re-injected through the control system. Additionally, a noise budget tool was developed to assess real-time noise impacts, and a proper system identification approach was applied to the Filter Cavity of the Frequency Dependent Squeezing system, yielding promising results for more complex setups. Future directions include refining noise characterization, use of advance system identification techniques and completing optical setups for testing new materials and coatings at cryogenic temperatures, essential for next-generation observatories like the Einstein Telescope.