Quantum computers seem the subject of science fiction, but their tremendous computational potential is closer than we may think. Despite significant practical difficulties, small quantum devices of 5 to 7 bits have been built in the laboratory. Silicon technologies promise even greater scalability. To use these technologies effectively and help guide quantum device research, computer architects must start designing and reasoning about quantum processors now. However, two major hurdles stand in the way. First, compactly describable rules that characterize silicon-based quantum computing technologies are not known. Second, there is no infrastructure to design, test, and evaluate architectural alternatives. Our research focuses on overcoming both of these hurdles.