Jan Harms is Assistant Professor at the Gran Sasso Science Institute. He is chair of the Virgo and co-chair of the LIGO Newtonian-noise working groups with the task to develop systems to mitigate terrestrial gravity noise. His main research focus has been to conceive and to investigate technologies that will lead to sensitivity improvements in future gravitational-wave detectors, which includes the characterization of alternative detector concepts. This requires improving our understanding of fields such as quantum optics, thermodynamics, terrestrial gravity, and methods such as machine learning and modern data-analysis techniques.