UC Berkeley

Cosmic microwave background (CMB) polarization anisotropies are at the forefront of modern cosmology, and a detection of B-mode polarization due to inflationary gravitational waves is among the most sought-after discoveries in astrophysics. Current constraints on these primordial B-modes set their amplitude at ~10 nK, posing extraordinary technological challenges to the design, characterization, and performance of today's CMB observatories. An effective CMB telescope requires both excellent sensitivity and tight control of systematic effects, and advancements in telescope instrumentation, calibration hardware, and analysis techniques are needed for a robust extraction of the inflationary signal. In this dissertation, we present two primary research products that improve the scientific prospects of today's CMB experiments. First, we describe a Python simulation code to optimize the mapping speed of both existing and future instruments. This calculator conglomerates the best aspects of several existing codes to offer a generalized, feature-filled software both for modeling future experiments and for characterizing operating ones. We discuss its use within Simons Array (SA) and Simons Observatory (SO), as well as its broader utility to upcoming experiments, including CMB-S4. Second, we present new polarization modulators for SA, including an ambient-temperature, continuously rotating half-wave plate (HWP) for POLARBEAR-2a and a cryogenic HWP for POLARBEAR-2b. Continuously rotating HWPs are powerful tools to mitigate atmospheric 1/f noise and telescope-induced intensity-to-polarization leakage, and their effectiveness is increasingly important to a precise characterization of cosmic polarization. The HWPs described in this thesis introduce several optical, mechanical, and electrical hardware advancements, and we discuss how these HWPs are paving the way for similar modulators on POLARBEAR-2c and SO's small aperture telescopes.