Google reports 40-fold error reduction on Willow quantum chip

Google researchers reported a 40-fold reduction in errors while preparing key quantum computing resources on the company’s Willow processor, a laboratory result they say addresses a major obstacle to building useful quantum computers. The study, published in Science on October 15, produced logical T states with approximately 99.99% fidelity, a measure of accuracy. The technique, called magic state cultivation, prepares special quantum states needed for certain operations in general-purpose, fault-tolerant computing. Google says some estimates suggest producing these states could consume as much as 95% of a quantum computer’s capacity, leaving fewer resources for other calculations. Cultivation works by testing a noisy initial state through a series of checks and discarding attempts that fail. The states that pass are retained and developed into cleaner resources. About 8% of attempts passed every check, according to descriptions of the research. The approach therefore improves the quality of retained states while filtering out most attempts. The experiment also demonstrated transferring cultivated states between two error-correction methods, from a distance-3 color code to a...