KAIST Advances Quantum Computing with Innovative Magnetic Technology

In a groundbreaking achievement, researchers at the Korea Advanced Institute of Science and Technology (KAIST) have successfully demonstrated the potential of magnetic materials in quantum computing, marking a significant milestone in the field. This pioneering work, part of KAIST's Global Singularity Research Project, addresses the question: "Can we build a quantum computer using magnets?"

On May 6, 2025, KAIST announced that a team led by Professor Kab-Jin Kim from the Department of Physics has developed a 'photon-magnon hybrid chip' in collaboration with the Argonne National Laboratory and the University of Illinois Urbana-Champaign (UIUC). This technology enables real-time, multi-pulse interference using ferromagnetic materials, a first in the world.

The research demonstrates how a special chip can synchronize light and internal magnetic vibrations—known as magnons—facilitating the transmission of phase information between distant magnets. This vital step illustrates that magnetic materials can play a crucial role in quantum computing, potentially leading to the development of more efficient quantum information processing devices.

In essence, magnons, which arise from the collective spin vibrations of aligned atoms, exhibit unique properties such as nonreciprocal information transport. This characteristic makes them ideal for isolating quantum noise in compact quantum chips, which is a significant challenge faced by current quantum computing technologies. Furthermore, when coupled with both light and microwaves, magnons may pave the way for long-distance quantum communication over kilometers.

Professor Kim explained, "This project began with a bold, even unconventional idea proposed to the Global Singularity Research Program: 'What if we could build a quantum computer with magnets?' The journey has been fascinating, and this study not only opens a new field of quantum spintronics, but also marks a turning point in developing high-efficiency quantum information processing devices."

The innovative research team utilized two small magnetic spheres made of Yttrium Iron Garnet (YIG), strategically placed 12 mm apart, with a superconducting resonator positioned between them. This setup mirrors configurations used in quantum processors developed by industry leaders such as Google and IBM. By inputting electrical pulses into one magnet, the researchers successfully achieved lossless transmission of magnon vibrations to the second magnet through the superconducting circuit.

The researchers confirmed that from single nanosecond pulses to a series of four microwave pulses, the magnon vibrations maintained their phase information, demonstrating coherent interference. This breakthrough signifies the first time that electrical signals have been employed to manipulate magnonic quantum states, paving the way for quantum gate operations—a fundamental technique in quantum information processing—using a hybrid system of magnetic materials and superconducting circuits.

The findings were published in two prominent journals: Nature Communications on April 1, 2025, and npj Spintronics on April 17, 2025. The first paper, titled "Single-shot magnon interference in a magnon-superconducting-resonator hybrid circuit," elucidates the mechanics behind this technology (DOI: https://doi.org/10.1038/s41467-025-58482-2). The second paper, "Single-shot electrical detection of short-wavelength magnon pulse transmission in a magnonic ultra-thin-film waveguide," further explores its implications (DOI: https://doi.org/10.1038/s44306-025-00072-5).

The research was funded by KAIST's Global Singularity Research Initiative, the National Research Foundation of Korea, and the U.S. Department of Energy, highlighting the international collaborative effort to push the boundaries of quantum computing technology.

As the field of quantum computing rapidly evolves, this innovative approach by KAIST not only reveals the potential of magnetic materials in quantum applications but also sets the stage for future advancements that may lead to room-temperature quantum computing without the constraints of cryogenic systems. With ongoing developments in this area, the implications for quantum technology could be transformative, affecting industries ranging from telecommunications to computing and beyond.