Google reports lower quantum-state errors in Willow chip experiment
In short
Google said its quantum AI team demonstrated a technique on the Willow chip that reduced errors in particular quantum states by about a factor of 40. Chinese reports said the resulting states reached 99.99% accuracy and the research appeared in Science.
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Google said its quantum AI team had demonstrated Magic State Cultivation on the Willow quantum chip, reducing the error rate of particular quantum states by about a factor of 40, according to Yicai and cnBeta. The reports said the resulting states achieved 99.99% accuracy, described by cnBeta as logical fidelity for T states. They said the research had been published in Science. [ 2 , 3 ]
The method addresses the preparation of special quantum states needed to perform operations for complex calculations. Yicai reported Google's explanation that quantum computers are susceptible to interference and errors, while producing these states consumes substantial computing resources. Both reports cited estimates that traditional preparation could use as much as 95% of a quantum computer's capacity, leaving fewer resources for calculations themselves. [ 2 , 3 ]
The cultivation process detects errors and discards unsuitable states, according to the reports. cnBeta described injecting a noisy state into a small region of a quantum chip, followed by coordinated measurements to filter out faulty samples. It said the comparison showing the 40-fold error reduction was against states that had not undergone cultivation. [ 2 , 3 ]
cnBeta also reported that the researchers encountered noise associated with electrical equipment drift and temperature fluctuations during testing. The team adjusted controls and developed a benchmarking approach using the cultivation technique itself, the outlet said. It further described a demonstration transferring a state from a distance-three color code to a distance-five surface code, two forms of quantum error correction. [ 2 ]
Yicai reported that Google presented the work as a step toward practical quantum computing because it could reduce resources devoted to error correction. The company also said further validation was needed to determine whether the technique could be applied to larger-scale systems. The reported results concern a specific state-preparation experiment. [ 2 , 3 ]
Why it matters
The technique targets the resource-intensive preparation of special states needed for complex quantum calculations. Google said further work is needed to establish whether it can be applied to larger quantum systems.
Key facts
- Google demonstrated a technique called Magic State Cultivation on its Willow quantum chip, the reports said. [ 2 , 3 ]
- The reported error reduction concerns prepared quantum states, rather than all chip operations. [ 2 , 3 ]
- The reports put the resulting state accuracy or logical fidelity at 99.99%. [ 2 , 3 ]
- Yicai reported that larger-scale applicability remains to be verified. [ 3 ]
Confirmed by several sources
Still unclear
- Whether the technique will work in larger quantum computing systems. Yicai reported that Google said this still requires validation.