Weird Brand-New Superconductor Could Help Make Quantum Computers Stable

Close-up of the material shows deformation due to repeated cooling cycles. Thilo Bauch and Floriana Lombardi/Chalmers University of Technology

Quantum computers have the capacity to revolutionize our ability to communicate and simulate reality, but many obstacles need to be overcome before these new devices realize their full potential. Now researchers might have found a way to take a step forward.

Calculations in quantum computers harness the power of quantum mechanics, but the system they use tends to be delicate. One of the most promising building blocks is called a Majorana fermion, a special particle that is also its own antiparticle. They don’t suffer from decoherence, which makes them stable and excellent for quantum computers.

While the particles look great on paper, in solid state materials they can only be found in a type of theoretical superconductor known as a topological superconductor. Now, researchers at the Chalmers University of Technology have managed to actually make a topological superconductor for the first time. Their results are published in Nature Communications.

The researchers were not specifically looking to construct such an interesting material. Instead, they were actually interested in other approaches to superconductivity. They started with a special type of insulator made of bismuth telluride, which lets electric currents move only on its surface. Researchers placed platinum and aluminum on the surface and then cooled the whole block down to almost absolute zero. At this point the aluminum becomes superconducting, meaning that it conducts electricity with no electrical resistance.

The surface of the bismuth telluride material becomes superconducting too. But researchers realized that after repeated cooling cycles, the superconducting properties were changing and depended on the direction that the electrons were moving in – a hallmark of topological superconductivity. Further analysis supports the idea that they created such material.  

“Our experimental results are consistent with topological superconductivity,” senior author Floriana Lombardi, Professor at the Quantum Device Physics Laboratory at Chalmers, said in a statement. “For practical applications the material is mainly of interest to those attempting to build a topological quantum computer. We ourselves want to explore the new physics that lies hidden in topological superconductors – this is a new chapter in physics.”

The team considers it likely that warming and cooling the bismuth telluride block caused stresses in the material, which might have led to it demonstrating the unusual property. We are still very much at the dawn of quantum computing but it will be interesting to see if the topological superconductor can deliver!


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