The Cryotron Remembered

[Sean Haas] is a “harmful freelance historian,” and his current discuss on the Classic Pc Pageant in Southern California covers the cryotron — an odd detour on the street to computer systems circa 1956. The NSA wished a pc to interrupt codes, however in 1956, there wasn’t a lot to select from, particularly since they wished a really quick laptop.

As you would possibly anticipate from the identify, a cryotron relies on superconductivity. The unique machine was a tantalum wire wrapped with a niobium wire coil. When the machine is soaked in liquid helium, each wires develop into superconducting. The tantalum wire can carry far more present in that state except the niobium coil generates a magnetic area, which kills the wire’s superconductivity. On the plus aspect, you may have a relay-like change that works with no shifting components. On the destructive aspect, you want liquid helium.

Common Electrical produced one of many first built-in circuits containing a skinny movie cryotron, which was flat. Whereas the switching was quick, it wasn’t as quick because it might be, so marrying the cryotron with a Josephson junction improved the machine to the place it may change at lower than 800 picoseconds. That isn’t all that outstanding immediately, however that was a technical feat within the Nineteen Fifties and Sixties.

In the event you get pleasure from [Sean’s] discuss, you would possibly wish to learn the original paper from 1955 from [Dudley Buck]. We’ve appeared again at the device before (and you may nonetheless find the broken link). Seems you are able to do lots with a Josephson junction.

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