Overview
- Google Quantum AI published the experiment in Science on Thursday and reported that cultivation on its Willow processor cut magic‑state errors roughly 40 times and produced T‑states with 99.99% logical fidelity.
- Cultivation works by injecting a noisy magic state into a small patch, running coordinated measurements that reject flawed attempts, and then growing the surviving state into a larger, error‑protected encoding.
- The team also demonstrated 'grafting' by moving a cultivated state from a distance‑3 color code into a distance‑5 surface code, showing the purified state can transfer between common error‑correction schemes on real hardware.
- The run used at most 54 of Willow’s 105 physical qubits and passed full quality checks only about 8% of the time, so yield, larger‑scale demonstrations, and further hardware noise reduction remain key engineering gaps.
- Magic states have long been a major resource bottleneck for universal quantum computing and cultivation was proposed by Google researchers in 2024; the result is a lab milestone that narrows one bottleneck but keeps cryptographic threats and practical applications far off without much larger and cleaner systems.