Novel process for patterning quantum materials

Jülich, July 29, 2019 - Implementing quantum materials in computer chips gives access to fundamentally new technologies. For example, to build powerful and error-resistant Quantum Computers, one can combine topological insulators with superconductors. This process step is associated with some challenges, which have now been solved by researchers from Jülich. Their results are presented in the current issue of the journal Nature Nanotechnology.

Even the ancient Incas used knots in cords to encode and store information in their ancient script "Quipu". What is the advantage? Well, 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. For this, however, no cord is knotted, but so-called quasiparticles in space and time.

To build such a quantum knot machine, new materials are needed: so-called quantum materials. Experts speak of topological insulators and superconductors. Processing these materials into components for Quantum Computers is a challenge in itself; especially because topological insulators are very sensitive to air.

Scientists at Jülich have now developed a novel process that allows quantum materials to be patterned without being exposed to air during processing. The so-called "Jülich process" thereby allows superconductors and topological insulators to be combined in an ultrahigh vacuum to produce complex components.

Initial measurements in their samples show evidence of Majorana states. "Majoranas" are precisely the promising quasiparticles that will be knotted in the networks of topological insulators and superconductors shown to enable robust quantum computing. In a next step, the researchers from the Peter Gruenberg Institute, together with their colleagues from Aachen, the Netherlands and China, will equip their networks with readout and control electronics to make the quantum materials accessible for application.

a) Scanning electron micrograph during the "Jülich process": A chip during fabrication can be seen. The topological insulator (colored red) has already been selectively deposited. In a next fabrication step, the superconductor is deposited via shadow mask deposition. In black and white, different mask systems can be seen, which make it possible to manufacture the desired components completely in ultra-high vacuum. b) In such networks one wants to try in the future to shift so called Majorana modes (shown as stars) along the topological tracks to enable topologically protected quantum computing operations. While the blue and violet Majorana modes remain at the same position (x,y) in space, the green and white modes rotate around each other over time, thus forming a node in spacetime.
Forschungszentrum Jülich / Peter Schüffelgen

Original publication:
'Selective area growth and stencil lithography for in situ fabricated quantum devices' by Peter Schüffelgen, Daniel Rosenbach, Chuan Li, Tobias W. Schmitt, Michael Schleenvoigt, Abdur R. Jalil, Sarah Schmitt, Jonas Kölzer, Meng Wang, Benjamin Bennemann, Umut Parlak, Lidia Kibkalo, Stefan Trellenkamp, Thomas Grap, Doris Meertens, Martina Luysberg, Gregor Mussler, Erwin Berenschot, Niels Tas, Alexander A. Golubov, Alexander Brinkman, Thomas Schäpers and Detlev Grützmacher
Nature Nanotechnology, 29 July 2019, DOI: 10.1038/s41565-019-0506-y

Further information:

Peter-Grünberg-Institut, Halbleiter-Nanoelektronik (PGI-9)

Video (PHD Comics, in Englisch): How To Tie A Quantum Knot


Prof. Detlev Grützmacher
Peter-Grünberg-Institute, Semiconductor Nanoelectronics (PGI-9)
Forschungszentrum Jülich
Tel.: +49 2461/61-2340

Dr. Peter Schüffelgen
Peter-Grünberg-Institute, Semiconductor Nanoelectronics (PGI-9)
Forschungszentrum Jülich
Tel: +49 2461 61-85250

Press contact:

Dr. Regine Panknin
Press officer, Forschungszentrum Jülich
Tel.: +49 2461 61-9054

Last Modified: 12.08.2022