Researchers at Chalmers University of Technology edge closer to quantum computing breakthrough

Researchers claim first in race to manufacture a component able to host Majorana particles

Researchers at Chalmers University of Technology claim to have become the first to manufacture a component able to host a 'Majorana particle', that is, a subatomic particle that could become stable building blocks of a quantum computer.

Majorana fermions are highly original particles, unlike those that make up the materials around us. In highly simplified terms, they can be seen as half electron.

In quantum computing, the idea is to encode information in a pair of Majorana fermions that are separated in the material, which should, in principle, make the calculations immune to decoherence.

Our experimental results are consistent with topological superconductivity

However, the problem with Majorana particles is that they only occur under very special circumstances due to their sensitivity to decoherence and thus collapsing of superpositions. In solid state materials, for example, they only appear to occur in what are known as topological superconductors - a fresh type of superconductor that is that it is hardly ever found in practice.

This is what makes it difficult for scientists to build a successful quantum computer.

Nevertheless, the researchers at Chalmers University claim to be the first in the world to submit results indicating that they have actually succeeded in manufacturing a topological superconductor.

"Our experimental results are consistent with topological superconductivity," said Floriana Lombardi, professor at the Quantum Device Physics Laboratory at Chalmers.

To create their unconventional superconductor they started with what is called a topological insulator made of bismuth telluride, or Be2Te3. A topological insulator is mainly just an insulator and thus does not conduct current, but it conducts current in a very special way on the surface.

The researchers placed a layer of a conventional superconductor on top, in this case aluminium, which conducts current entirely without resistance at really low temperatures.

"The superconducting pair of electrons then leak into the topological insulator which also becomes superconducting," explained Thilo Bauch, Associate Professor in Quantum Device Physics.

Lombardi's researchers used platinum to assemble the topological insulator with the aluminium. Repeated cooling cycles gave rise to stresses in the material, which caused the superconductivity to change its properties

However, the initial measurements all indicated that they only had standard superconductivity induced in the Bi2Te3 topological insulator.

But when they cooled the component down again later, to routinely repeat some measurements, the situation suddenly changed and the characteristics of the superconducting pairs of electrons varied in different directions.

"And that isn't compatible at all with conventional superconductivity. Suddenly unexpected and exciting things occurred," added Lombardi.

Unlike other teams, Lombardi's researchers used platinum to assemble the topological insulator with the aluminium. Repeated cooling cycles gave rise to stresses in the material, which caused the superconductivity to change its properties.

After many analyses the research team established that they had succeeded in creating a topological superconductor.

"For practical applications the material is mainly of interest to those attempting to build a topological quantum computer," added Lombardi. We ourselves want to explore the new physics that lies hidden in topological superconductors; this is a new chapter in physics."