Quantinuum explores alternative route to fault-tolerant quantum computing

Quantinuum researchers have demonstrated a technique for fault-tolerant quantum computing that could reduce reliance on magic state distillation, one of the most resource-intensive techniques used in many quantum computing architectures.

The researchers achieved this by demonstrating a universal set of quantum gates using non-Abelian anyons, a type of quasiparticle that could enable a topological approach to quantum computing.

Topological quantum computing aims to make quantum computers more resistant to errors by spreading quantum information across many qubits rather than storing it in individual ones. Because the information is distributed across the system, it is less vulnerable to local sources of noise.

Anyons are quasiparticles that emerge in certain quantum systems rather than fundamental particles. Non-Abelian anyons are particularly interesting because moving them around one another changes the quantum state in a way that depends on the order of the exchanges. This allows researchers to perform quantum operations by repeatedly exchanging, or “braiding,” anyons in different orders. Because the outcome depends on the order of those exchanges, the encoded information is naturally protected from certain types of errors.

The work, published in Nature and carried out with researchers from Caltech, the University of Chicago and Harvard University, created a topologically ordered state across 54 qubits on Quantinuum’s H2 trapped-ion processor. The researchers then encoded logical information in non-Abelian anyons before combining braiding and fusion to implement a universal set of quantum gates.

Previous topological approaches could not produce a universal gate set through braiding alone. In the new work, the researchers combined braiding with anyon fusion, allowing them to demonstrate a universal set of quantum gates and prepare a so-called magic state.

Magic states are specially prepared quantum resources that enable certain quantum operations that cannot be performed directly on error-corrected logical qubits. Producing them is resource-intensive and typically requires large numbers of physical qubits, making magic state distillation one of the biggest overheads in many fault-tolerant quantum computing architectures.

By demonstrating that magic states can instead be prepared using topological operations, the work points to one possible route to reducing those hardware requirements.

The experiment was performed on Quantinuum’s H2 trapped-ion quantum processor, which has previously been used in demonstrations of quantum error correction and logical qubits.

The demonstration does not replace conventional quantum error correction, and significant work remains to determine whether the approach can scale. However, it adds another candidate approach to the growing range of architectures being investigated for fault-tolerant quantum computing and could ultimately reduce the resources needed to build practical systems.