Quantum leap for superconductors

A research group at Delft University of Technology in the Netherlands has discovered one-way superconductivity without the use of magnetic fields, something that was thought to be impossible ever since its discovery in 1911 – until now.

Throughout the 20th century, many scientists, including Nobel laureates, have struggled over the nature of superconductivity. Discovered in 1911 by Dutch physicist Kamerlingh Onnes, superconductors have since been a holy grail effort by researchers due to their near-limitless pros and virtually no cons.

In superconductors, a current flows across a wire with no resistance, which means inhibiting this current or even blocking it is hardly possible – let alone getting the current to flow only one way and not the other.

Associate professor Mazhar Ali and his research group at TU Delft, however, have managed to achieve the remarkable task of one-directional superconducting, which is necessary for computing. That is to say; it's like inventing a special type of ice that has zero friction one way but insurmountable friction the other.

The advantages of applying superconductors to electronics are twofold. Superconductors can make electronics hundreds of times faster, and incorporating superconductors into our daily lives would make information technology much more eco-friendly. For example, if you spun a superconductor wire from the Earth to the Moon, it would transport the energy without any loss.

According to the Dutch Research Council, using superconductors instead of conventional semiconductors could save up to 10% of all Western energy reserves.

Throughout the 20th century and into the 21st, however, no one could tackle the barrier of making superconducting electrons go in just a single direction, which is a fundamental property needed for computing and other modern electronics. In normal conduction, the electrons fly around as separate particles; in superconductors, they move in pairs of twos without any loss of electrical energy.

In the 1970s, scientists at IBM tried out the idea of superconducting computing but had to stop their efforts. In their papers on the subject, IBM mentioned that without non-reciprocal superconductivity, a computer running on superconductors is impossible.

Ali goes on to explain why superconductivity never worked compared to semiconductors, stating that "where we slap together two semiconductors: one has extra electrons and the other has extra holes. The separation of charge makes a net built-in potential that an electron flying through the system will feel. ... similar to if you were swimming with the river or swimming up the river."

So how has this been such an issue for scientists for over a century?

"Superconductors never had an analog of this one-directional idea without magnetic field; since they are more related to metals than semiconductors, which always conduct in both directions and don't have any built-in potential," he answered in an interview with SciTechDaily.

For the team, the discovery was mainly due to exploration into 2D quantum materials, which researchers are discovering every day do not necessarily apply the laws of physics as we understand it.

"We used the quantum material Nb3Br8 (niobium-bromine), which is a 2D material like graphene that has been theorized to host a net electric dipole (a pair of equal and oppositely charged or magnetized poles separated by a distance), as our quantum material barrier of choice and placed it between two superconductors," said Ali.

"We were able to peel off just a couple atomic layers of the Nb3Br8, and make a very, very thin sandwich – just a few atomic layers thick," Ali continued.

As to what this may mean for future technologies, it is much more than saying next-generation or cutting-edge.

"Technology that was previously only possible using semiconductors can now potentially be made with superconductors using this building block," continued Ali. "This includes faster computers, as in computers with up to terahertz speed, which is 300 to 400 times faster than computers we are now using. This will influence all sorts of societal and technological applications."

As for stable replication, the team says the first hurdle to tackle for any commercial application is raising the operating temperature, with the next step being to investigate how to scale production to millions of Josephson diodes (also known as a Josephson junction, which are materials that are considered good candidates for the construction of quantum bits or qubits) which classifies on a chip.

A discovery of this magnitude has surely shaken the computing world, and with a starting point now clearly visible, a world of supercomputing may be just around the corner

"If the 20th century was the century of semiconductors, the 21st century can become the century of the superconductor," finished Ali.