Determining the origin of structure in the universe is one of the most important open
problems in cosmology. CMB anisotropies sourced by early-universe density perturbations
are currently the most powerful observational probe of the earliest mechanisms of structure
formation. It is possible that the same processes that produced the density perturbations also
sourced tensor perturbations, or primordial gravitational waves (PGWs). If this is the case,
detecting a PGW signal would yield insight into physics far earlier than the epoch of …

CMB-S4---the next-generation ground-based cosmic microwave background (CMB)
experiment---is set to significantly advance the sensitivity of CMB measurements and
enhance our understanding of the origin and evolution of the Universe, from the highest
energies at the dawn of time through the growth of structure to the present day. Among the
science cases pursued with CMB-S4, the quest for detecting primordial gravitational waves
is a central driver of the experimental design. This work details the development of a …