Department of Physics

RPTU contributing to “MagSQuant”: New low-loss materials for quantum technology

Magnonic microwave isolator based on two microscopic antennas (made of gold) for the generation and detection of magnons in the underlying film of yttrium iron garnet (YIG)
Magnonic microwave isolator based on two microscopic antennas (made of gold) for the generation and detection of magnons in the underlying film of yttrium iron garnet (YIG). The orientation of the external magnetic field H breaks the symmetry of the system, which is why magnons can only propagate in one direction (in this case downwards). As a result, a microwave signal only flows from the upper to the lower antenna and not vice versa, creating a directional isolator. Figure: Philipp Pirro
Magnonic microwave insulator including its microwave leads on a film of yttrium iron garnet (YIG)
Magnonic microwave insulator including its microwave leads on a film of yttrium iron garnet (YIG). Illustration: Philipp Pirro

The joint project “Low-loss materials for integrated magnonic-superconducting quantum technologies” (MagSQuant) is a new initiative aimed at significantly increasing the performance and scalability of superconducting quantum platforms. The project is being funded as part of the “Quantum Systems” research programme of the German Federal Ministry of Education and Research (BMBF) with a funding amount of 2 million euros and will run until 30 September 2027. The aim of MagSQuant is to develop materials that minimize losses in quantum systems and advance the integration of miniaturized components. RPTU is one of the research partners in the project, which is coordinated by the Leibniz Institute for Crystal Growth (IKZ) in Berlin.

The challenges in scaling quantum computers and technologies are considerable. Superconducting circuits, which are currently considered a key technology in quantum technology, are limited by energy losses and the high space requirements of conventional microwave components. MagSQuant aims to overcome these hurdles by developing novel materials that enable low-loss, miniaturized and integrable components. These components are to be based on magnetic and superconducting circuits and thus open up new possibilities for the production of high-performance quantum systems.

To realize the vision of a hybrid integration of miniaturized magnetic and superconducting circuits, the project partners are researching new material solutions. A key element is the development of magnetic thin films that exhibit long-lasting magnetic excitations - so-called magnons. These materials will be based on a special oxide substrate thin-film system that guarantees a particularly long magnon lifetime at the ultra-low operating temperatures of superconducting circuits. The use of high-purity zone-melted silicon substrate crystals will also improve the relaxation times of the superconducting quantum bits and thus increase the efficiency and stability of the quantum technology based on them.

By providing these new materials and miniaturized components, MagSQuant is making an important contribution to the further development of quantum technologies. On the one hand, the materials developed within the framework of MagSQuant promote the scalability and performance of quantum systems for industrial applications and, on the other hand, they open up new application possibilities for gas-phase epitaxial coatings and liquid-phase epitaxy. The results from MagSQuant are of great interest to numerous users of superconducting quantum circuits and magnetic excitations, as they enable improved overall performance.

The joint project is coordinated by the Leibniz Institute for Crystal Growth (IKZ) in Berlin and includes as partners the Association for the Promotion of Innovation through Research, Development and Technology Transfer (INNOVENT e.V.) in Jena, the Rhineland-Palatinate Technical University Kaiserslautern-Landau and the Friedrich-Alexander University Erlangen-Nuremberg. The network coordinator is Dr. Christo Guguschev from the IKZ.

Research contribution of the RPTU
A team at RPTU led by Professor Mathias Weiler and Junior Professor Philipp Pirro is contributing its expertise in magnon research. They are developing magnonic components that act as microwave insulators and shield the superconducting quantum bits from external interference like a protective shield. These components are also so small that they take up less than a hundredth of a square millimeter on a chip.

Source: News from Leibniz Institute for Crystal Growth (IKZ)

Magnonic microwave isolator based on two microscopic antennas (made of gold) for the generation and detection of magnons in the underlying film of yttrium iron garnet (YIG)
Magnonic microwave isolator based on two microscopic antennas (made of gold) for the generation and detection of magnons in the underlying film of yttrium iron garnet (YIG). The orientation of the external magnetic field H breaks the symmetry of the system, which is why magnons can only propagate in one direction (in this case downwards). As a result, a microwave signal only flows from the upper to the lower antenna and not vice versa, creating a directional isolator. Figure: Philipp Pirro
Magnonic microwave insulator including its microwave leads on a film of yttrium iron garnet (YIG)
Magnonic microwave insulator including its microwave leads on a film of yttrium iron garnet (YIG). Illustration: Philipp Pirro