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Scientists discover ‘revolutionary’ one-way superconductor

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A research group at Delft University of Technology has made a groundbreaking discovery that could pave the way towards superconducting computing

The research team, led by associate professor Mazhar Ali, has found a way to enable one-way superconductivity without magnetic fields, something that was thought to be impossible ever since its discovery in 1911 – until today.

The findings, published in Nature, make use of 2D quantum materials and pave the way towards superconducting computing, something that could make electronics hundreds of times faster, all with zero energy loss.

“If the 20th century was the century of semi-conductors, the 21st can become the century of the superconductor,” said Ali.

Since superconductivity's discovery, many scientists, including Nobel Prize winners, have puzzled over the challenge of making superconducting electrons go in just one direction. 

In superconductors, a current goes through a wire without any resistance, which means blocking or inhibiting this current is almost impossible. In the 1970s, scientists at IBM tried out the idea of superconducting computing but had to stop their efforts, stating that without non-reciprocal superconductivity, a computer running on superconductors was impossible.

This is why Ali’s group’s ability to make superconducting one-directional is remarkable, comparable to inventing a special type of ice which gives you zero friction when skating one way, but insurmountable friction the other way.

This discovery can pave the way for significant improvements in the speed and efficiency of current connectivity and even a faster path to fusion. If you were to spin a superconducting wire from here to the Moon, it would transport the energy without any loss. Moreover, the use of superconductors instead of regular semi-conductors might save up to 10 per cent of all western energy reserves, according to NWO.

“There is a difference in going in the same direction as the dipole versus going against it; similar to if you were swimming with the river or swimming up the river,” Ali explained.

In what the team calls 'Quantum Material Josephson Junctions', the researchers replaced the classical barrier material in Josephson Junctions – sandwiches of two superconductors with non-superconducting classical barrier materials in-between the superconductors – with a quantum material barrier, where the quantum material's intrinsic properties can modulate the coupling between the two superconductors in novel ways.

For example, in the Josephson diode, the team used the quantum material Nb3Br8, a 2D material similar to graphene, as the quantum material barrier of choice and placed it between two superconductors.

The team was able to “peel off just a couple atomic layers of this Nb3Br8 and make a very, very thin sandwich”, which was needed for making the Josephson diode and was not possible with normal 3D materials.

“Superconductors never had an analogue of this one-directional idea without magnetic field,” said Ali.

Technology that was previously only possible using semi-conductors can now potentially be made with superconductors using this building block. This includes faster computers with up to terahertz speed, which is 300 to 400 times faster than the computers we are currently using.

The scientists are now looking at raising the operational temperature and scaling of production in order to ensure commercial application of the Josephson diodes.

“There is a very real chance, if the challenges are overcome, that this will revolutionise supercomputing!” said Ali.

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