One of the big goals of today’s CMB experiments is to look for the faint signature of primordial gravitational waves in the B-mode polarization. Finding it would give us a unique window into the physics of the very early Universe and the Inflationary epoch.
In this talk, I will introduce the physics of CMB polarization and review the current observational landscape. I will present preliminary maps from the Simons Observatory, discuss the role of both ground-based and space-based experiments, and outline ongoing efforts in preparation for the LiteBIRD space mission. I will also highlight recent work at SISSA on the development of robustness tests, designed to assess the reliability of component separation and to ensure readiness for a possible future detection of the B-mode signal.