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Implementing quantum materials in computer chips provides access to fundamentally new technologies. In order to build powerful and fault-resistant quantum computers, it is possible, for example, to combine topological insulators with superconductors. This process step brings with it some challenges that have now been solved by researchers from Jülich.
Image Caption: a) Scanning electron micrograph during the "Jülich process": A chip can be seen during fabrication. The topological insulator (dyed red) has already been selectively deposited. In a next fabrication step, the superconductor is applied via shadow mask deposition. In black-and-white, various mask systems are recognizable which make it possible to manufacture the desired components completely in ultrahigh vacuum. b) In such networks one wants to try to move so-called majorana modes (represented as stars) along the topological tracks in order to enable topologically protected quantum computing operations. While the blue and violet Majorana fashion stays in the same position (x, y) in the room. Credit: Forschungszentrum Jülich / Peter Schüffelgen
Even the ancient Inca used knots in cords to encode and store information in their ancient writing "Quipu". The advantage: unlike ink on a sheet of paper, the information stored in the knot is robust against external destructive influences, such as water. Even novel quantum computers should be able to store information robustly in the form of nodes. For this, however, no cord is knotted, but so-called quasi-particles in space and time.
What is needed to build such a quantum node machine are new materials called quantum materials. Experts speak of topological insulators and superconductors. The processing of these materials to components for quantum computers is a challenge in itself; especially because topological insulators are very sensitive to air.
Scientists in Jülich have now developed a novel process that makes it possible to structure quantum materials without exposing them to air during processing. The so-called "Jülich process" makes it possible to combine superconductors and topological insulators in ultrahigh vacuum to produce complex components.
Initial measurements in their samples indicate evidence of majorana states. "Majoranas" are exactly the promising quasiparticles to be knotted in the shown networks of topological insulators and superconductors to enable robust quantum computing. In a next step, the researchers of the Peter Grünberg Institute, together with their colleagues from Aachen, the Netherlands and China, will provide their networks with readout and control electronics in order to make the quantum materials available for the application.