Relazione su invito
Ground-based Cosmic Microwave Background polarization observations.
Cosmic Microwave Background (CMB) is one of the most sensitive tool to investigate the very early universe. The last frontier in this field is the quest for B mode on large angular scales, directly probing the stochastic background of gravitational waves predicted by the inflationary paradigm. The detection of this extremely weak signal passes through a deep knowledge of systematic effects, both of instrumental and astrophysical in origin. In this contribution I shall review the status of the ground-based activities, with a particular focus on two international experiments, QUBIC and LSPE-STRIP, where the Italian community plays a major role.