Magnon Breakthrough Could Shrink Quantum Computers to the Size of a Penny

Physics Magnon Breakthrough Could Shrink Quantum Computers to the Size of a PennyBy University of ViennaMay 28, 20264 Mins Read Facebook Twitter Pinterest Telegram LinkedIn WhatsApp Email Reddit Share Facebook Twitter LinkedIn Pinterest Telegram Email Reddit Researchers have shown that elusive magnetic excitations can survive far longer than previously thought, opening new possibilities for ultra-compact quantum devices. Credit: ShutterstockPhysicists at the University of Vienna have discovered magnons with lifespans that are one hundred times longer.Magnons are tiny waves of magnetization that move through solid magnetic materials, similar to ripples spreading across water after a stone falls in. Unlike photons, which can move through empty space or optical fibers, magnons travel inside magnetic solids.Their wavelengths can shrink to the nanometer scale, which means magnonic circuits could, in theory, fit onto chips as small as those used in modern smartphones. Because magnons are excitations within a solid, they can naturally interact with many other fundamental quasiparticles, including phonons and photons, making them promising components for hybrid quantum systems and quantum metrology.The main limitation has been their extremely short lifetime. Until now, magnons could reliably carry quantum information for only a few hundred nanoseconds at best, which is far too brief for practical quantum computing.The team led by Wiener has now reported a major advance, measuring magnon lifetimes of up to 18 microseconds, almost one hundred times longer than any previous observation, paving the way for a quantum computer the size of a 1-cent coin. At that scale, magnons stop behaving like short-lived signals and begin to resemble dependable carriers of quantum information, comparable to the superconducting qubits used in today’s leading quantum processors. The findings were recently published in the journal Science Advances.Colder crystals revealed the limitThe advance came from combining two strategies. First, instead of using conventional uniform magnons, the team generated short wavelength magnons, which are naturally less affected by defects on the crystal surface. Those surface defects had limited magnon lifetimes in earlier experiments.Second, the researchers placed extremely pure spheres of yttrium iron garnet (YIG) inside a mixed phase cryostat and cooled them to just 30 millikelvin, only a tiny fraction above absolute zero. At such low temperatures, the thermal processes that normally destroy magnons are effectively frozen out.From right to left, Rostyslav Serha, Andrii Chumak, David Schmoll and Sebastian Knauer are standing in front of a cryostat. This device is used to generate and stabilise extremely low temperatures. Credit: Ian EhmThe team also showed that the remaining limit on magnon lifetime is not set by a basic law of physics. Instead, it depends on tiny trace impurities inside the crystal. The researchers tested three spheres with different purity levels and found a clear pattern: purer material allowed magnons to last longer. Even the least pure sample outperformed all previous records. That means future improvements may depend mainly on better materials science rather than on uncovering new physics.What this means for quantum technologyA lifetime of 18 microseconds could turn magnons from weak intermediate links into strong quantum memories and efficient communication channels on a chip. They may be able to connect hundreds of qubits through a shared pathway, serving as a long awaited quantum bus for scalable quantum computers.Because magnons exist in a solid material and can interact with many different quantum systems, they could also act as universal translators in hybrid quantum architectures, connecting technologies that otherwise cannot easily communicate with one another.Reference: “Ultralong-living magnons in the quantum limit” by Rostyslav O. Serha, Kaitlin H. McAllister, Fabian Majcen, Sebastian Knauer, Timmy Reimann, Carsten Dubs, Gennadii A. Melkov, Alexander A. Serga, Vasyl S. Tyberkevych, Andrii V. Chumak and Dmytro A. Bozhko, 1 May 2026, Science Advances. DOI: 10.1126/sciadv.aee2344This material is based on the work supported by the National Science Foundation under award no. DMR-2338060 (D.A.B.).

This research was funded in whole or in part by the Austrian Science Fund (FWF) project no. 10.55776/I6568 (A.V.C.) and Deutsche Forschungsgemeinschaft (DFG, German Research Foundation)—TRR 173—268565370 Spin+X (Projects B01 and B04) (A.A.S.).Never miss a breakthrough: Join the SciTechDaily newsletter.Follow us on Google and Google News.Quantum Mechanics Quantum Physics Quasiparticles Spintronics University of Vienna Share.

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