Recent developments in high speed superconducting devices

The factors controlling the speed of useful cryotron circuits are: circuit geometry, insulation thickness, resistivity of superconducting film in normal state, superconducting and transition properties of films used. These factors are discussed in detail and in addition new circuit techniques are described that increase the speed of operation to the millimicrosecond range. A new type of cryotron is mentioned that introduces a significantly larger resistance in the normal state. This device is particularly useful for driving long lines such as encountered in cryogenic memory planes.