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Researchers at the Forschungszentrum Jülich develop novel process for structuring quantum materials

The so-called "Jülich process" makes it possible to combine superconductors and topological insulators in the ultra-high vacuum and thereby produce complex components.

3 months ago by Forschungszentrum Jülich GmbH

Already the Inca used knots in cords in their ancient writing “Quipu” to encode and store information. The advantage: Unlike ink on a sheet of paper, the information stored in the knots is robust against external destructive influences such as water. Novel quantum computers should also be able to store information robustly in the form of knots. However, this does not require knotting a cord, but knotting space and time (Fig. 1b).

What you need to build such a quantum-knot-machine are new materials, so called quantum materials. Experts speak of topological insulators and superconductors. The processing of these materials into components for quantum computers is a challenge in itself, especially because topological insulators are very air-sensitive.

Scientists at the Forschungszentrum 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 (yellow) and topological insulators (red) in the ultra-high vacuum and thereby produce complex components (Fig. 1a). The researchers present their results in the current issue of the journal Nature Nanotechnology.

a) Scanning electron micrograph taken during the Jülich process: Shown is a die during fabrication. The topological insulator (indicated in red) has already been deposited selectively. In a next fabrication step, the superconductor is deposited via shadow mask evaporation. In black and white various mask systems can be identified. These masks make it possible to manufacture the desired quantum devices completely under ultra-high vacuum conditions. b) In such networks, researchers aim at shifting so-called Majorana modes (represented by stars) along the traces defined by the topological insulators in order to perform topologically protected quantum operations. While the blue and violet Majorana stay at the same position (x,y) in space, the green and white Majorana twist around each other during time, performing a knot in space-time.

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First measurements in their devices show indications of Majorana states. “Majoranas” (indicated as stars in Fig. 1b) are precisely the promising quasiparticles that are to be knotted in the shown networks of topological insulators and superconductors in order to enable robust quantum computing. In a next step, the researchers at the Peter-Grünberg Institute 9 will equip their networks with read-out and control electronics in order to make the quantum materials accessible for application.