The IEEE Spectrum Magazine published recently a popular article on superconducting computing by David C. Brock, who recently became director of the Center for Software History at the Computer History Museum. The description of the ongoing IARPA C3 program on energy efficient computing is preceded by a historical overview of various superconducting computing concepts and R&D programs over the past six decades.
The URL of that article is:
http://spectrum.ieee.org/computing/hardware/will-the-nsa-finally-build-its-superconducting-spy-computer.