Exotic particles called nonabelions could fix quantum computers' error problem
The coat of arms of Italy's aristocratic House of Borromeo contains an unsettling symbol: an arrangement of three interlocking rings that that cannot be pulled apart but doesn't contain any linked pairs. That same three-way linkage is an unmistakable signature of one of the most coveted phenomena in quantum physics — and it has now been observed for the first time. Researchers have used a quantum computer to create virtual particles and move them around so that their paths formed a Borromean-ring pattern. The exotic particles are called non-Abelian anyons, or nonabelions for short, and their Borromean rings exist only as information inside the quantum computer. But their linking properties could help to make quantum computers less error-prone, or more 'fault-tolerant' — a key step to making them outperform even the best conventional computers. The results, revealed in a preprint on 9 May1, were obtained on a machine at Quantinuum, a quantum-computing company in Broomfield, Colorado, that formed as the result of a merger between the quantum computing unit of Honeywell and a start-up based in Cambridge, UK. "This is the credible path to fault-tolerant quantum computing," says Tony Uttley, Quantinuum's president and chief operating officer. Other researchers are less optimistic about the virtual nonabelions' potential to revolutionize quantum computing, but creating them is seen as an achievement in itself. "There is enormous mathematical beauty in this type of physical system, and it's incredible to see them realized for the first time, after a long time," says Steven Simon, a theoretical physicist at the University of Oxford, UK. Basket-weave doughnut In the experiment, Henrik Dreyer, a physicist at Quantinuum's office in Munich, Germany, and his collaborators used the company's most advanced machine, called H2, which has a chip that can produce electric fields to trap 32 ions of the element ytterbium above its surface. Each ion can encode a qubit, a unit of…