The study of nonlinearities in nature suitable for computer use has led to the cryotron, a device based on the destruction of superconductivity by a magnetic field. The cryotron, in its simplest form, consists of a straight piece of wire about one inch long with a single-layer control winding wound over it. Current in the control winding creates a magnetic field which causes the central wire to change from its superconducting state to its normal state. The device has current gain, that is, a small current can control a larger current; it has power gain so that cryotrons can be interconnected in logical networks as active elements. The device is also small, light, easily fabricated, and dissipates very little power.

The Cryotron-A Superconductive Computer Component

Frequency Standard at Low Temp

Cryostatic arrangements range from simple, thermally rather isolated objects, through immersion baths, to those for precision calorimetry. Electric controls range from manual through simple proportional, to combinations of proportional, rate and reset, employing thermocouples or resistance thermometers.

Wide-Range Cryostat Temperature Control

Considering potential practical applications of low-temperature phenomena, a general survey is made of the temperature dependence of noise and electrical resistance down to the region of Absolute Zero. It is shown that the signal-to-noise ratio in a metallic resistor can be increased by lowering its temperature, while cooling has little effect on carbon resistors. The theory of electrical conductance in metals is reviewed, and it is determined that whenever ohmic losses are important as in an inductance, decreasing the temperature can be a help. The phenomenon of superconductivity is treated, including use of the superconducting properties of certain metals in the construction of a very sensitive bolometer and in the frictionless suspension of a lead sphere.

Clayton A. Swenson

Papers

Low-Temperature Electronics