Quantum Computing’s “Dark Horse” Just Cleared a Major Hurdle

Physicists have made a big step forward in quantum computing. They showed that special quantum objects called non-Abelian anyons can perform all the operations needed for a universal quantum computer. This means these anyons could help build more versatile and reliable quantum machines.

Researchers from the University of Chicago, Harvard, Stony Brook University, and Quantinuum worked together on this project. Their experiments are the first to prove that this method can support all universal quantum operations.

A New Way to Compute

Ruben Verresen, a professor at UChicago, explained that they demonstrated a "universal gate set." This means if you store information in these "emergent versions of quarks" and move them around, you can do any quantum calculation you want.

This new method could lead to quantum computers that are not only general-purpose but also more reliable. Regular quantum computers protect information by spreading it across many qubits. However, these methods often can't do every operation directly on the protected information.

Often, engineers use "magic states" to get around this. But creating these states takes a lot of effort and uses up many qubits. The new findings suggest that non-Abelian anyons might avoid this expensive step.

Henrik Dreyer from Quantinuum noted that non-Abelian codes are a "dark horse" in quantum error correction. He added that this work shows fault-tolerant computations can be done without needing magic state distillation, which is usually the most costly part of standard quantum error correction.

How Anyons Work

Regular qubits store information as a zero, a one, or a mix of both. Non-Abelian anyons are different. They aren't natural particles. Instead, researchers create them using quantum circuits that link many ordinary qubits into a shared, entangled state. This state then acts like a new type of particle with its own rules.

Verresen described these codes as creating "little universes" that reflect some properties of our own.

Each non-Abelian anyon has an internal state that changes when it moves, or "braids," around another anyon. The order of these movements matters, allowing anyons to represent and control information in unique ways.

Their information is also spread across many entangled qubits, making it more resistant to small disturbances that often affect regular qubits. The braiding process both protects the information and performs a computational gate.

Braiding and Fusion for Universal Computing

In 2024, Verresen and others created anyons based on D4 symmetry using a Quantinuum trapped-ion computer. This was the first time this type of non-Abelian order was shown in hardware. However, these anyons couldn't perform all the operations needed for universal computing.

For their latest work, the team chose a different symmetry called S3, which relates to an equilateral triangle. They created these anyons on Quantinuum's H2 trapped-ion processor, using 54 entangled qubits.

S3 had the right mathematical properties for universal computing, but braiding alone wasn't enough. The researchers also needed "fusion," where two anyons are brought together, and the result is measured.

An emergent quark moves around an obstacle and, through this braiding process, gradually changing its internal color label. Because there are three possible colors (R, B, and G) this degree of freedom forms a qutrit. Slightly altering the path does not change the result, which gives a sense of the stability of the braiding process. Credit: University of Chicago

This theoretical idea was first proposed in 2003 by Carlos Mochon. Turning it into a working procedure on real quantum hardware required more development and testing.

The researchers paired the anyons to encode "topological qutrits," which store three levels of quantum information instead of the usual two. They then combined braiding and fusion to show three key operations: one entangling gate from braiding and two distinct measurements from fusion.

These operations, in theory, can create any quantum operation, including those braiding alone couldn't achieve. These quantum states might also help physicists study basic properties of matter.

Anasuya Lyons and Chiu Fan Bowen Lo, graduate students at Harvard, noted how rewarding it was to see these ideas realized in the lab, thanks to recent advances in quantum hardware.

The team also created a magic state directly from the non-Abelian anyons using topological operations. This avoids the costly distillation process usually needed in other quantum systems.

The Next Steps: Error Correction

The researchers did not use active error correction in these experiments. Instead, they focused on testing the individual computational parts and confirming they worked as expected. They also verified that the resulting magic state matched theoretical predictions.

Verresen explained that this work is more of a "proof of principle." The next challenge is to combine this method with active error correction. This could eventually make non-Abelian anyons a practical foundation for large-scale, fault-tolerant quantum computers. Verresen is already working on ways to stabilize non-Abelian quantum memories.

Deep Dive & References

Universal gates from braiding and fusing anyons on quantum hardware - Nature, 2026