A pdf from the National Security Agency that assesses the potential of superconducting technology. It includes an assessment of Rapid Single Flux Quantum (RSFQ). RSFQ is a digital electronics technology that relies on quantum effects in superconducting materials to switch signals, instead of transistors. However, it is not a quantum computing technology in the traditional sense. They project 100,000 josephson junctions at 50 GHz by 2010 and then a few years after 250 million jj at 250 GHz.