Argonne National Laboratory and the University of Illinois Urbana-Champaign have built the first hybrid circuit system coupling propagating spin waves in magnetic materials with a superconducting circuit. Researchers demonstrated how ripples in a material’s magnetic state, spin waves, can interact with superconducting circuits, creating a system where these two methods of carrying information work together.
“This is the first time we’ve shown the proof of concept, demonstrating that we can couple spin waves to a superconducting resonator,” said Yi Li, an Argonne scientist. This coupling uses the naturally one-directional flow of spin waves to potentially improve signal control and reduce noise in quantum systems.
Yttrium Iron Garnet Enables One-Way Spin Wave Coupling
Yttrium iron garnet’s exceptional ability to sustain magnetic motion underpins a newly realized hybrid circuit, minimizing energy loss as spin waves propagate through the material. This precise layering allows spin waves traveling within the film to excite microwaves in the superconducting layer, effectively creating an efficient on-chip antenna tuned for interaction. The resulting strong coupling between spin waves and microwaves enables a key feature: one-way propagation of a hybrid mode, directing information flow along a single path within the circuit.
“One-way propagation is important because it can help guide information in a single direction and reduce unwanted return signals,” explained Li, highlighting the benefit for quantum information science and the integration of this control onto a superconducting circuit. This unidirectional flow is a departure from previous attempts to couple magnetic spins to superconducting circuits, which relied on Kittel modes that do not inherently support one-way signal transmission.
This design represents a shift toward more compact, on-chip systems suitable for future quantum technologies, as the team successfully transitioned the spin waves’ journey from the magnetic film into microwaves within the superconducting circuit. Valentine Novosad, an Argonne Distinguished Fellow, described the broader significance of this work, stating, “Shows a way to efficiently couple superconducting circuits with moving spin waves.” He further clarified that this experiment exemplifies the use of magnetic excitations, or spin waves, patterned onto a chip to communicate with a different type of electromagnetic wave residing within a superconducting resonator. The ability to control signal direction is paramount for quantum systems, preventing disruptive noise from re-entering sensitive quantum components and maintaining the integrity of information.
Axel Hoffmann, a Founder professor at U. of I., emphasized the exploratory nature of their work, noting, “In quantum information engineering, we dig into different material systems to explore exotic material properties, see which materials can do something special or power modern technologies.” He framed the team’s approach as a question of identifying what unique capabilities magnetic materials can offer to advance the field. The successful demonstration of this platform, after previous challenges in achieving material compatibility, marks a step toward realizing practical on-chip microwave isolators.
These devices would allow microwave signals to travel in one direction within spin-wave-based hybrid quantum systems, an important component for building more stable and reliable quantum processors. “Nobody had succeeded in doing so before because of the materials challenge. Now we’ve shown that this platform works,” the researchers report, indicating a resolution to a long-standing obstacle in the field. The team’s work demonstrates a functional system where magnetic excitations and superconducting circuits can effectively communicate.
One-way propagation is important because it can help guide information in a single direction and reduce unwanted return signals.
Yi Li, an Argonne scientist and first author of the paper, published in Physical Review Letters
Hybrid System Links Spin Waves to Superconducting Resonators
The newly demonstrated system achieves unidirectional signal flow by coupling magnetic excitations within a thin film to microwaves generated in a superconducting resonator. This interaction, described as a hybrid approach similar to a hybrid vehicle’s engine and motor, allows for the translation of information between fundamentally different carriers, spin waves and electromagnetic waves, within a single device. The ability to direct signal propagation is critical for minimizing noise and maintaining the integrity of quantum information.
The fabrication of these superconducting resonators was performed for Nanoscale Materials, a DOE Office of Science user facility at Argonne, highlighting the importance of advanced facilities in enabling this research. The convergence of spin-wave magnonics and superconducting quantum circuits represents a promising avenue for expanding the frontiers of quantum information science. The team views this work as part of a broader trend gaining momentum globally.
“This is a new field, an emerging field, and it is attracting attention around the world,” Novosad observed. The potential for combining the unique properties of these two distinct areas of research could lead to novel approaches for storing, manipulating, and transmitting quantum information.
The researchers express optimism about the future of hybrid systems in the context of quantum technologies, stating, “We see this result as part of a bright future for hybrid systems connected to quantum information science.” This initial demonstration establishes a functional platform for further exploration and refinement of these hybrid quantum systems.
Everything that is happening around us, everything we know, everything that comes to us comes in the form of a wave.
Argonne Distinguished Fellow Valentine Novosad, an Argonne scientist and the paper’s lead corresponding author
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