A practical, large-scale quantum computer must eventually possess the same level of versatility as a modern laptop—capable of running a vast array of different software applications and executing any type of quantum algorithm requested of it. For years, the path to such "universal" quantum computing has been hindered by the inherent fragility of qubits and the enormous resource costs associated with error correction. Now, a multi-institutional team of researchers from the University of Chicago Pritzker School of Molecular Engineering (UChicago PME), Harvard University, Stony Brook University, and the quantum computing company Quantinuum has demonstrated a new, highly flexible approach to this challenge using exotic quantum objects known as non-Abelian anyons.
The study, published in the journal Nature, marks the first experimental proof that these emergent quantum phenomena can support the full, broad range of operations required for universal quantum computation. By creating and testing a complete set of operations based on these anyons, the team has provided a potential roadmap for building more efficient and robust quantum machines.
"We demonstrated a so-called universal gate set—meaning that if you store information in these emergent versions of quarks, and you move them around, you can do any quantum computation you might want to do," explained Ruben Verresen, an assistant professor of molecular engineering at UChicago PME and a co-author of the new study.
A Possible Shortcut Around Costly Quantum Error Correction
The primary bottleneck in current quantum research is the extreme vulnerability of qubits to environmental noise and decoherence. To combat this, researchers typically employ complex error-correction protocols, which involve distributing a single unit of logical information across a vast number of physical qubits. While these methods are essential for preserving data, they are often incomplete; they rarely provide every individual operation necessary to perform universal quantum computation on that protected information.
To bridge this gap, engineers have traditionally relied on a technique known as "magic state distillation." This is an intensive, resource-heavy purification process that consumes a significant fraction of a quantum computer’s available qubits. Because these qubits are already scarce, the reliance on magic states creates a significant overhead that slows progress toward truly scalable machines. The new findings suggest that non-Abelian anyons could fundamentally change this landscape, offering a way to perform necessary operations without the prohibitive cost of standard distillation.
"Non-Abelian codes are a dark horse in the race to quantum error correction," said Henrik Dreyer, managing director and scientific lead at Quantinuum’s Munich office and a co-author of the study. "In this work, we show the first universal gate set in a non-Abelian code, which demonstrates that fault-tolerant computations can in principle be done without resorting to magic state distillation or cultivation, which are the most expensive operations in standard quantum error correction codes."
Why Non-Abelian Anyons Are Different
To understand the significance of this work, one must first distinguish between ordinary qubits and the non-Abelian anyons utilized by the team. Standard qubits encode information using two basic states—0 and 1—and the various quantum superpositions of those states. Non-Abelian anyons, however, operate on entirely different principles.
These anyons are not fundamental particles that can be found floating in nature. Instead, they are "emergent" phenomena created within a quantum circuit. By entangling a large number of conventional qubits into a specific collective state, researchers can create a system that behaves as though it contains new, exotic particles governed by their own unique rules.
"The way I think about these codes is they’re creating little universes—alternative universes, but ones that reflect some of the properties of our own," Verresen said.
Each non-Abelian anyon carries an internal state that is altered when one anyon is moved around another in a process called "braiding." The crucial aspect of these systems—and the reason they are called "non-Abelian"—is that the sequence of these braiding operations matters significantly. If you swap the order of the braids, you get a different result. This inherent sensitivity allows information to be encoded and manipulated in ways that are simply impossible with ordinary particles. Furthermore, because this information is distributed across many entangled qubits rather than trapped in a single location, it gains a level of natural protection against the localized disturbances that plague conventional quantum hardware.
Why Braiding Alone Was Not Enough
The team’s recent success builds upon foundational work conducted in 2024. In that earlier study, a team including Verresen utilized a Quantinuum trapped-ion computer to create anyons associated with a mathematical symmetry group known as D4, which represents the rotations and reflections that leave a square unchanged. While that experiment was a landmark achievement—marking the first time this form of non-Abelian order was demonstrated on quantum hardware—it had limitations.
While the team proved that these unusual particles could be created and manipulated, the braiding operations themselves were not powerful enough to facilitate universal quantum computing. "In that work, we didn’t demonstrate that those emergent forces were enough to do quantum computation," Verresen noted. "That particular universe we created was not powerful enough."
Fusion Unlocks Universal Quantum Operations
For the latest study, the researchers shifted their focus to a different symmetry known as S3—the set of rotations and mirror-image flips that leave an equilateral triangle unchanged. By leveraging Quantinuum’s H2 trapped-ion processor and utilizing 54 entangled qubits, they successfully created the corresponding S3 anyons.
The researchers discovered that while the S3 system possessed the necessary properties for universal quantum computation, braiding alone was insufficient. To achieve the full range of operations, they had to combine braiding with a secondary process known as "fusion," where two anyons are brought together and their resulting state is measured. This concept had been theorized as early as 2003 by Carlos Mochon, then a student of John Preskill at Caltech, but translating that theoretical blueprint into a functional experiment on modern hardware required years of iterative development.
By using pairs of anyons to encode "topological qutrits"—which store three possible levels of quantum information rather than the two levels found in standard qubits—the researchers created a more versatile computational space. Through the careful combination of braiding and fusion, the team demonstrated three key computational tools: one entangling gate produced via braiding and two distinct types of measurements created through fusion. These tools, when working in concert, can theoretically produce any quantum operation, effectively overcoming the limitations that hindered the previous D4 experiment.
The researchers highlighted the interdisciplinary nature of the project, noting how far the technology has evolved. "It is gratifying to see ideas we have spent our PhD work thinking about realized in the lab, and it has been made possible by remarkable advances in quantum hardware over the past few years," said Anasuya Lyons and Chiu Fan Bowen Lo, graduate students at Harvard University in the group of Ashvin Vishwanath, who were instrumental in leading the effort.
Toward Fault-Tolerant Quantum Computers
Beyond the immediate goal of building a better computer, this work offers a window into fundamental aspects of physics. The team also demonstrated that non-Abelian anyons could be used to directly produce a "magic state" using topological operations, effectively bypassing the distillation process that currently consumes so much of a quantum computer’s processing power.
While the current experiment functioned as a proof-of-principle—meaning it did not incorporate active, real-time error correction—it confirmed that the fundamental building blocks of the method work exactly as theoretical models predict.
"So far, we’ve ignored the question of error correction. Here, it’s more like a proof of principle," Verresen said. The next phase of research will focus on integrating these operations with active error-correction protocols. If successful, this approach could provide the foundation for a new generation of large-scale, fault-tolerant quantum computers. Verresen and his colleagues at UChicago PME are already looking toward the next horizon, investigating new techniques for stabilizing non-Abelian quantum memories, which could eventually pave the way for machines capable of solving problems far beyond the reach of today’s most powerful supercomputers.
