The discovery that neutrinos have nonzero, but inexplicably small, masses hints that these particles may hold a key to physics beyond the Standard Model. In this talk, I will discuss the search for neutrinoless double beta decay (0νββ), a proposed form of radioactive decay which is only possible if neutrinos and antineutrinos are their own antiparticles. A discovery of 0νββ would immediately demonstrate new physics, specifically establishing a) violation of lepton number conservation, b) the generation of neutrino masses by a mechanism other than the Higgs, and c) possible connections between neutrino interactions and the dominance of matter over antimatter in the universe. In this talk, I will describe the next generation of these experiments, focusing in particular on the nEXO experiment. nEXO is designed to push two orders of magnitude beyond the reach of current experiments, which requires the ability to detect just one 0νββ decay event per year in a volume of ~10^28 atoms. I will describe how nEXO will achieve this exquisite sensitivity, then discuss how its unique capabilities may enable other science in the field of particle astrophysics. I will close with a discussion on scaling up the techniques used by nEXO to enable beyond-the-next-generation searches for new physics.