Cryotron is a tiny electronic switching device that operates at very low temperatures. Cryotrons work on the principle of superconductivity, the ability of some metals, such as lead, to conduct electric current with no resistance at temperatures below –355 °F (–215 °C), or near absolute zero (see Absolute zero). Cryotrons are only about 0.1 inch (2.5 millimeters) long—so small that 100 of them will fit into a thimble. The small size of the device makes it possible to greatly reduce the size of computers and other electronic apparatus.
In some cryotrons, a superconducting coil of fine wire is wound around another superconducting wire. A flow of current through the coil produces a magnetic field, an area around a magnet where the magnet’s force can be felt. See Electricity (Electromagnetism). The other wire will conduct current with no resistance as long as no current flows through the coil. By regulating the flow of current in the coil, the flow in the second wire can be turned on or off, enabling the cryotron to operate as a switch. In another type of cryotron, thin superconducting film is used in place of fine wire. A container of liquid helium surrounds cryotrons and cools them to the low temperatures necessary for their operation.
Dudley A. Buck, a scientist at the Massachusetts Institute of Technology in the United States, began work on the cryotron in 1954.
See also Superconductivity.
