Scientists have reported in a study published in journal Nature Communications that they may have created an unconventional superconductor that could provide for Majorana particles, which are also called Majorana fermions. These particles could become stable building blocks of a quantum computer.
Majorana particles are seen as the building blocks for future quantum computers because of their insensitivity to decoherence. However, these particles only occur under very special circumstances. Majorana fermions are highly original particles, quite unlike those that make up the materials around us. In highly simplified terms, they can be seen as half electron. In a quantum computer the idea is to encode information in a pair of Majorana fermions which are separated in the material, which should, in principle, make the calculations immune to decoherence.
Scientists explain that these particles appear in topological superconductors – a new type of superconductor that is so new and special that it is hardly ever found in practice. However, scientists behind the new study have managed to reveal through experimental results that their superconductor could be consistent with topological superconductor.
To create their unconventional superconductor they started with what is called a topological insulator made of bismuth telluride, Be2Te3. A topological insulator is mainly just an insulator – in other words it does not conduct current – but it conducts current in a very special way on the surface. The researchers have placed a layer of a conventional superconductor on top, in this case aluminium, which conducts current entirely without resistance at really low temperatures.
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 – the characteristics of the superconducting pairs of electrons varied in different directions.
Unlike other research teams, the team behind the latest study used platinum to assemble the topological insulator with the aluminium. Repeated cooling cycles gave rise to stresses in the material (see image below), which caused the superconductivity to change its properties. After an intensive period of analyses the research team was able to establish that they had probably succeeded in creating a topological superconductor.