A team of physicists has overcome a major hurdle in quantum computing by significantly extending the lifetime of magnons, tiny magnetic waves that can carry quantum information. Researchers have extended its lifetime from just a few hundred nanoseconds to 18 microseconds. This is almost 100 times what was previously achieved. This progress could eventually enable the development of ultra-small quantum computers the size of a dime.
An international research team led by Andriy Chumak from the University of Vienna also revealed important insights. They discovered that the lifetime of a magnon is ultimately not limited by the laws of physics, but rather by the quality of the material through which it passes. Their discovery is scientific progress.
What is Magnon?
Magnons are small waves of magnetization that travel through magnetic solids. It can be compared to the ripples that spread out in a pond after a stone is dropped into water. Unlike photons, which pass through empty space or optical fibers, magnons remain inside magnetic materials.
Magnon-based circuits can be scaled down to wavelengths of just a few nanometers, potentially fitting into chips as large as those already found in smartphones. Magnons also naturally interact with other fundamental quasiparticles, including phonons and photons, making them attractive building blocks for hybrid quantum systems and quantum metrology.
Solving the magnon lifespan problem
One of the biggest challenges facing Magnon technology over the years has been its very short lifespan. Since they can only survive for a few hundred nanoseconds, they disappear too quickly to reliably store or transfer quantum information.
New research changes that. By extending the lifetime of magnons to 18 microseconds, the researchers turned these once-instantaneous signals into long-lasting carriers of quantum information. Its performance now approaches the timescales needed for practical quantum technologies, and magnons are comparable to the superconducting qubits used in today’s leading quantum processors.
How did researchers achieve their breakthrough?
This breakthrough was made possible by combining two important technologies.
First, instead of using traditional homogeneous magnons, the team generated short wavelength magnons. These are naturally less susceptible to the small defects in the crystal surface that shortened the lifetime of magnons in previous experiments.
The researchers then cooled the ultrapure spheres of yttrium iron garnet (YIG) to just 30 millikelvin in a mixed-phase cryostat. At temperatures just one degree above absolute zero, the thermal processes that normally destroy magnons are effectively frozen.
Materials, not physics, determine the limits
Perhaps the most surprising discovery was identifying what currently limits the lifespan of magnons.
By testing three YIG spheres at different purity levels, the researchers found a distinct pattern. The purer the crystal, the longer the magnon can survive. Even the least pure samples outperformed all previous experiments.
This result suggests that future improvements will depend primarily on advances in materials science, rather than overcoming inevitable laws of nature. As researchers develop even purer magnetic materials, magnon lifetimes are likely to continue to improve.
Why this matters for quantum computing
Once the lifetime reaches 18 microseconds, the magnon becomes more than a temporary signal. These could serve as reliable quantum memory devices and low-loss communication channels to move quantum information across the chip.
Researchers say Magnon could eventually connect hundreds of qubits through a shared pathway, creating a long-awaited “quantum bus” that could help scale future quantum computers. Because magnons naturally interact with many different quantum systems, they can also act as universal translators, allowing technologies that normally cannot communicate with each other to work together.
The study is based on experiments conducted by Rostislav Selha during his doctoral research. The project was led by the University of Vienna in collaboration with the University of Colorado Colorado Springs and research institutions in Germany, the United States, and Ukraine. Co-author Caitlin McAllister joined us through the Vienna Physics PhD Program, which offers internships to talented master’s students from around the world.
