Researchers from Germany, the Netherlands, and the United States produced the breakthrough, which challenges a century of thinking about the nature of superconducting circuits and how their currents may be managed and put to practical use.
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 kind of electrical current so useful also make creating superconducting versions of conventional electrical components a never-ending task.
Consider a diode, which is a rather simple device. This fundamental unit of electronics functions as a one-way sign for currents, allowing you to control, convert, and adjust electron flow.
The identity of those individual electrons blurs in superconducting materials, resulting in Cooper pairs, which allow each particle in the partnership to avoid the energy-sapping jostling of a more 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 can’t break reciprocity (at least not without manipulating the magnetic field) – has been held since the field’s inception.
To be honest, it’s a stumbling block that engineers could do without.
“In the 1970s, IBM scientists experimented with superconducting computing but were forced to abandon their efforts: IBM mentions in their papers on the subject that a computer running on superconductors is impossible without non-reciprocal superconductivity,” researchers explain in a press release about their new study.
In the aftermath of 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.
Previously, an external magnetic field could be used to ensure that this current only ever flows in 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 few atomic layers of this Nb3Br8 and make a very, very thin sandwich – just a few atomic layers thick – which was required for making the Josephson diode and was not possible with normal 3D materials,” says 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 discovery. 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 pressures.
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 have an impact on a wide range of societal and technical applications,” Ali adds.
“If the twentieth century was the century of semiconductors, the twenty-first century has the potential to be the century of superconductors.”
This study was published in the journal Nature.