Each newly added qubit improves accuracy disproportionately. “If this were not the case, the resources required for error correction would grow so rapidly that the advantages of quantum algorithms themselves would be eliminated,” writes Sven Ramelow and Helen Chrzanowski in their commentary on the study for Science Media. Both are also researching quantum systems at Humboldt University in Berlin.
Another important step forward in the current study is the fact that the Google team has maintained this error correction mechanism for over 50 computational cycles. The error rate was partially at a level necessary for the actual use of a quantum computer.
In contrast, independent experts rated the implementation of a method that is more complex, but more relevant to practice than superficial code, as not yet sufficient. Here, scientists at Google Quantum AI have not yet been able to reduce the error rate to the level required for real computations.
In general, the last step – linking the qubits including error correction so they can perform the calculations – is still pending. However, Innsbruck quantum computer expert Peter Zoller summed it up as a success through decisive technological improvements at all levels in the sycamore processor. “The path to righting wrong is a marathon; progress in that direction is gradual but remarkable.”