![]() ![]() ![]() Quantum computer race intensifies as alternative technology gains steam Quantinuum’s approach has an advantage: compared with most other types of qubit, the ions in its trap can be moved around and brought to interact with each other, which is how quantum computers perform computations. Each ion can encode a qubit, a unit of quantum computation that can be ‘0’ or ‘1’ like ordinary bits, but also a superposition of both states simultaneously. 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. “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. Other researchers are less optimistic about the virtual nonabelions’ potential to revolutionize quantum computing, but creating them is seen as an achievement in itself. “This is the credible path to fault-tolerant quantum computing,” says Tony Uttley, Quantinuum’s president and chief operating officer. The results, revealed in a preprint on 9 May 1, 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 firm based in Cambridge, UK. 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 exotic particles are called non-Abelian anyons, or nonabelions for short, and their Borromean rings exist only as information inside the quantum computer. Welcome anyons! Physicists find best evidence yet for long-sought 2D structures ![]() Researchers have used a quantum computer to create virtual particles and move them around so that their paths formed a Borromean-ring pattern. 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. The coat of arms of Italy’s aristocratic House of Borromeo contains an unsettling symbol: an arrangement of three interlocking rings that cannot be pulled apart but doesn’t contain any linked pairs. If any one of the three rings is removed, the other two are no longer joined. The authors note that more work is needed to reach logical error rates required for effective computation, but this work demonstrates a fundamental requirement for future developments.Borromean rings depicted in a church in Florence, Italy. The larger surface code was shown to enable better logical qubit performance (2.914% logical error per cycle) than the smaller surface code (3.028% logical error per cycle). They created a superconducting quantum processor with 72 qubits and tested it with two different surface codes: one called a distance-5 logical qubit (on 49 physical qubits), and smaller ones called distance-3 logical qubits (on 17 physical qubits). Hartmut Neven and colleagues at Google Quantum AI demonstrate that a surface code logical qubit can lower error rates as the system size increases. For logical performance to improve with increasing code size, the overall error correction needs to outweigh the additional logical errors. This system, called a surface code logical qubit, can detect and correct errors without affecting information, but scaling up such systems means manipulating more qubits, which may introduce more logical errors. One method of quantum error correction uses error-correcting codes, in which an ensemble of physical qubits (units of quantum information, equivalent to classical computer bits) form a logical qubit. Quantum computers, like their classical counterparts, are prone to errors caused by ‘noise’ (or disruption) from the underlying physical system realizing their potential requires the reduction of error rates. The work represents a step towards the development of scalable quantum error correction to enable quantum computers to reach sufficiently low error rates and run useful quantum algorithms. A demonstration of quantum computing where error rates decrease as the size of error correction increases is reported in Nature this week. ![]()
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