It seems like the basic building blocks of a topological quantum computer were demonstrated experimentally for the first time.
https://arxiv.org/abs/2601.20956
The promise of topological quantum computer – which would be resistant to errors because it would encode quantum information using trajectories of weird “quasiparticles” called anyons – is one of the main motivations why people investigate topological orders like fractional quantum Hall effect or spin liquids. The catch about this study is that, as far as I understand, it lacks the required stability, which arises from the fact that the topological order is exhibited by the ground state of the system (lowest energy), and the anyons are lowest excitations (lowest energies above the ground state). Here, as far as I understand, the topologically ordered state was created inside a quantum computer, with no reference to energy. Still, this is one step closer to realizing topological quantum computation. Also, the study uses quantum gates based both on anyon braiding – “winding” their trajectories around each other – and “fusion”, i.e. merging anyons with each other. I was not aware you can use fusion in this way.
#science #physics #quantum #CondensedMatter #CondMat #QuantumComputing #TopologicalOrder #anyons

Universal Topological Gates from Braiding and Fusing Anyons on Quantum Hardware
Topological quantum computation encodes quantum information in the internal fusion space of non-Abelian anyonic quasiparticles, whose braiding implements logical gates. This goes beyond Abelian topological order (TO) such as the toric code, as its anyons lack internal structure. However, the simplest non-Abelian generalizations of the toric code do not support universality via braiding alone. Here we demonstrate that such minimally non-Abelian TOs can be made universal by treating anyon fusion as a computational primitive. We prepare a 54-qubit TO wavefunction associated with the smallest non-Abelian group, $S_3$, on Quantinuum's H2 quantum processor. This phase of matter exhibits cyclic anyon fusion rules, known to underpin universality, which we evidence by trapping a single non-Abelian anyon on the torus. We encode logical qutrits in the nonlocal fusion space of non-Abelian fluxes and, by combining an entangling braiding operation with anyon charge measurements, realize a universal topological gate set and read-out, which we further demonstrate by topologically preparing a magic state. This work establishes $S_3$ TO as simple enough to be prepared efficiently, yet rich enough to enable universal topological quantum computation.



