An Improved Film Cryotron and Its Application to Digital Computers

A crossed film cryotron deposited on an insulated superconductor is described and analyzed. It has a time constant of less than one μsec and is approximately 100 times faster than the original crossed film cryotron [4]. The dc dissipation is less than five μw and the active area of each element is approximately 5×10-4 cm2. These cryotrons and all their interconnecting circuitry can be deposited at one and the same time in a few simple steps. A cryotron storage circuit and a shift register is described, based upon a principle unique to superconductors. The shift register shown is deposited in an area corresponding to 18,000 active elements per square foot. Calculations are presented to show that with this component density, a computer or memory containing more than one million elements can be operated in a one-cubic-foot container using a one-watt output liquid helium refrigerator.