# Google Quantum AI cuts magic-state errors about 40-fold on Willow with state cultivation

Canonical page: https://technooptimist.io/stories/google-quantum-ai-cuts-magic-state-errors-about-40-fold-on-willow-with-13b42f6e
Date: 15 Oct 2026
About: [Google Quantum AI](https://technooptimist.io/companies/google-quantum-ai.md) · [Willow and error-correction roadmap](https://technooptimist.io/quantum/willow.md)
Original source: https://blog.google/innovation-and-ai/models-and-research/quantum-computing/magic-state-cultivation-quantum-computing/

Google Quantum AI reports that magic state cultivation works on its Willow processor, a technique that filters flawed attempts to make the special states that universal quantum computers need. The team reports a logical fidelity of 99.99% and says the work, published in Science, is still at small scale.

## Key facts

- Magic states are needed for universal quantum computing but are costly to make; the authors cite estimates that up to 95% of a machine's capacity could go to producing them.
- Cultivation uses coordinated error-checking measurements as a filter, reducing errors about 40-fold compared with un-cultivated states.
- The team also showed grafting: moving a state from a distance-3 color code to a distance-5 surface code on the hardware.
- The authors say cultivation must be shown at larger scale before it is realistic for practical quantum computers.

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