Physicists Developed a Superconductor Circuit Long Thought to Be Impossible

Scientists have created a superconducting circuit capable of feats previously considered to be impossible by swapping a conventional material for one with unique quantum qualities.

Researchers from Germany, the Netherlands, and the United States produced the breakthrough, which challenges a century of thinking about superconducting circuits and how to control and use their currents.

Low-waste, high-speed circuits based on superconducting physics provide a unique chance to push supercomputing technology to new heights.

Unfortunately, the features that make this simple type of electrical current so useful also make superconducting versions of conventional electrical components a never-ending struggle to develop.

Consider the diode. This fundamental electrical component functions as a one-way sign for currents, allowing you to control, convert, and adjust electron motions.

The identities of those individual electrons blur in superconducting materials, resulting in Cooper pairs, which allow each particle in the partnership to dodge the energy-sapping jostling of a conventional electric current.

Scientists have been unable to make superconducting electrons go in a single direction without the regular rules of resistance at work, since they invariably exhibit'reciprocal' behavior.

This basic premise – that superconductivity cannot break reciprocity (at least not without manipulating the magnetic field) – has been held from the field's inception.

Frankly, it's a hurdle engineers could do without.

"In the '70s, scientists at IBM tried out the idea of superconducting computing but had to stop their efforts: in their papers on the subject, IBM mentions that without non-reciprocal superconductivity, a computer running on superconductors is impossible," researchers explain in a press release about their new study.

Following an experiment that demonstrates a sort of junction with a quantum component capable of steering even Cooper pairs down a one-way street, such efforts may need to be reviewed.

Josephson junctions are small strips of non-superconducting material that separate two superconducting materials. If the material is thin enough, electrons can pass through it without a second thought.

This 'supercurrent' has no voltage below a particular threshold. A voltage arises at a critical point, quickly oscillating in waves that can be used in quantum computing applications.

An external magnetic field was previously used to ensure that this current only ever went one direction. However, the researchers discovered that by using a 2D lattice based on the metal niobium, they could eliminate the field and depend entirely on the material's quantum features.

"We were able to peel off just a couple atomic layers of this Nb3Br8 and make a very, very thin sandwich – just a few atomic layers thick – which was needed for making the Josephson diode, and was not possible with normal 3D materials,"  bsays lead researcher Mazhar Ali of Delft University of Technology in the Netherlands.

The team believes they've checked all the boxes necessary to build a strong case for their finding. Still, superconductors have a long way to go before they become the backbone of next-generation computers.

For one thing, superconductivity is most commonly observed in materials cooled to just above absolute zero.

Some superconducting materials can withstand the heat, but only when subjected to extreme pressure.

Learning how Josephson junctions based on these new quantum barriers perform at greater temperatures and pressures might be a game-changer in the future, decreasing the amount of equipment required for tremendously efficient supercomputers never seen before.

"This will influence all sorts of societal and technological applications," Ali adds.

"If the 20th century was the century of semi-conductors, the 21st can become the century of the superconductor."

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