A team of Dutch researchers has successfully developed nanowires that allow individual electrons to be captured by a ‘quantum dot’ on which superconductivity can take place. Such nanowires could play a role in the development of quantum computers. The researchers from the MESA+ research institute of the University of Twente, the Delft University of Technology and the Eindhoven University of Technology report their research in a paper in Advanced Materials.
Quantum computers make use of the quantum properties of materials: properties that are only exhibited at a scale of a few dozen nanometers. This means that a quantum computer needs a completely different set of building blocks than a standard computer. Researchers all over the world are working to create such building blocks, but it is still unclear which materials will yield the best components.
"This is an ideal material for doing fundamental research that is relevant to the development of quantum computers. It’s the perfect material for investigating the best route towards this computer."Joost Ridderbos, University of Twente
The Dutch researchers have now successfully developed a new and interesting building block. They managed to create nanowires made of germanium and silicon in which individual electrons could be captured by ‘holes’ (the absence of an electron) in a ‘quantum dot’. This allowed superconductivity – a condition in which electricity moves through a medium with no resistance whatsoever – to occur through these quantum dots. The combination of a quantum dot and superconductivity makes it possible to create ‘Majorana fermions’, exotic particles that are their own antiparticle and which are regarded as an important component in the quantum computers of the future.
This is not the first time that scientists have succeeded in creating nanowires with quantum dots on them in which superconductivity can occur. It is, however, the first time that this has been done using nanowires with a germanium core and a silicon shell. According to Joost Ridderbos from Mesa+, the principal advantage of this material, besides its quantum properties, is that it is extremely well defined. This means it can be manufactured with great precision, with every single atom in the right place.
“I can’t say whether this is the material that will ultimately be used in quantum computers; I don’t have a crystal ball,” says Ridderbos. “What I can say is that this is an ideal material for doing fundamental research that is relevant to the development of quantum computers. It’s the perfect material for investigating the best route towards this computer.”
The researchers first produced a wire with a diameter of about 20nm and then fitted it with minuscule aluminum electrodes. At a temperature of 0.02K above absolute zero, they succeeded in demonstrating superconductivity in this wire, and with the help of an external electric field they created a quantum dot containing exactly one ‘electron hole’.
This story is adapted from material from the University of Twente, with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier. Link to original source.