With the first discovery of quasi-particles – called excitons – and topological insulators, an international group of scientists working at the Würzburg-Dresdner Cluster of Excellence ct.qmat has made progress (Milestone for electronic lighting control devices) in quantum research. This discovery laid the foundation for a new generation of computer chips and light-conducting quantum technology. This was done with a sharp invention from Würzburg – the birthplace of topological insulators. The research results have been published in the journal Nature Communications.
A new toolbox for solid state physics
When looking for new materials for future quantum technology, scientists at the ct.qmat Center of Excellence – Complexity and Topology of Quantum Materials at the University of Würzburg and Dresden are focusing, among other things , and topological insulators. These can conduct electricity without loss and store information well. The first-class experimental discovery of this material took place in Würzburg in 2007 and led to worldwide progress in rigorous scientific research that continues to this day.
Previous concepts of using topological insulators were based on applying an electrical voltage to control the channel – similar to the switching process on a normal computer chip. However, if the characteristics of the dangerous elements are based on the neutral elements – that is, they are not charged or negatively charged – the application of electrical voltage is no longer effective. Therefore, such a quantum display requires other devices to be able to be created – for example light.
Quantum physics combines optics and electronics
An international research team of Würzburg quantum physicist and ct.qmat spokesperson, Professor Ralph Claessen, has made a very important discovery: “For the first time, we have been able to create quasi-particles – called excitons – in a. With this, we have created a new toolbox for solid state physics, with the help of which we can manipulate electrons optically. This principle can become the basis for new types of applications,” says Claessen.
Excitons are electronic quasiparticles. They behave like particles in their own right, but it is a state of affairs that can only appear in certain quantum objects. “We created excitons by applying a small amount of light to a layer of material composed of a single atomic layer,” says Claessen. What is unusual about this is that the excitons are made to work in a topological insulator – which was not possible before. Claessen sums up, “We have opened up new avenues of research for insulators.
In the last decade, excitons and other two-dimensional semiconductors have been studied and studied as information carriers for controlled light. “We have now succeeded for the first time in optically stimulating excitons in a topological insulator. The interaction between light and excitons promises new things in such things. This can be used, for example, to create qubits,” says Classen.
Qubits are computational units of quantum chips. They are superior to each other and process tasks in minutes that would take supercomputers years. Using light instead of electrical voltage allows quantum chips to have faster clock rates. Therefore, the latest research results pave the way for future quantum technologies and a new generation of light-controlling devices and microelectronics. A world expert from Würzburg
The basis for this: the right starting material – in this case bismuth. “It’s the heavy brother of graphene, a miracle material,” says Claessen, who first designed the topological coating five years ago in the lab. “Here, we are world leaders,” he added. “Thanks to our ingenious design, the atoms in the bismuth monolayer are arranged in a honeycomb-like graphene. The difference is that bismuth is a topological insulator due to its heavy atoms and can conduct electricity without resistance, even at high temperatures. Graphene can’t do that.
Thoughts – great potential
After the research team was able to create excitons in a topological insulator for the first time, the focus is now on the quasiparticles themselves. Scientists at ct.qmat investigate whether the topological properties of bismuth are transferred to excitons. This scientific evidence is your next step. Then the path to the construction of topological qubits will be cleared, it is considered to be difficult compared to the non-topological example.
International relations
This research project is the result of a collaboration between scientists from Bologna, Wroclaw, New York, Oldenburg and Würzburg, creating a 2D model of bismuth at the University of Würzburg.
