Researchers from Karl Berggrens group in MITs Department of Electrical Engineering and Computer Science have found that,although traditionally operated as single photon detectors, superconducting nanowires host a suite of attractive characteristics that have recently inspired their use in digital circuit applications for amplification, addressing, and memory.

Here, I take advantage of the electrothermal feedback that occurs in resistively shunted nanowires to develop two new technologies: (1) A multilevel memory cell made by incorporating a shunted nanowire into a superconducting loop, allowing flux to be controllably added and stored; and (2) An artificial neuron for use in spiking neural networks, consisting of two nanowire-based relaxation oscillators acting analogously to the two ion channels in a biological neuron. By harnessing the intrinsic dynamics of superconducting nanowires, these devices offer competitive energy performance and a step towards bringing memory and processing closer together on the same platform, writes Berggren.

Berggren is resurrecting the Cryotron a concept described in1956, by MITs Dudley Buck and he calls his device a nano-cryotron.

In Berggrens device, current runs through a superconducting, supercooled wire called the channel. That channel is intersected by an even smaller wire called a choke like a multilane highway intersected by a side road. When current is sent through the choke, its superconductivity breaks down and it heats up. Once that heat spreads from the choke to the main channel, it causes the main channel to also lose its superconducting state.

Berggrens group has already demonstrated proof-of-concept for the nano-cryotrons use as an electronic component.

A former student of Berggrens, Adam McCaughan, developed a device that uses nano-cryotrons to add binary digits.

Berggren has used nano-cryotrons as an interface between superconducting devices and classical, transistor-based electronics.

He thinks the nano-cryotron could one day find a home in superconducting quantum computers and supercooled electronics for telescopes. Wires have low power dissipation, so they may also be handy for energy-hungry applications, he said.

Its probably not going to replace the transistors in your phone, but if it could replace the transistor in a server farm or data center? That would be a huge impact says Berggren.

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