Google Shows Magic State Cultivation Works on Its Willow Quantum Chip, Cutting Errors 40-Fold

In a paper published today in Science, Google Quantum AI shows a cheaper way to make the “magic states” quantum computers need for their most powerful operations, with errors about 40 times lower than its baseline method.

Researchers at Google Quantum AI, led by Emma Rosenfeld, published a study in Science on Oct. 15, 2026 showing that a technique called magic state cultivation works on real hardware, using Google’s Willow superconducting chip. A preprint of the work first appeared on arXiv in December 2025.

Quantum computers need special “magic states” to run non-Clifford gates (usually the T gate), the operations that give them power beyond ordinary computers. The standard way to make them, distillation, is costly: Rosenfeld told Scientific American that up to 95% of a quantum computer can end up devoted to producing them. Google researchers proposed cultivation in 2024 as a cheaper alternative that “grows” a single magic state in a small patch of qubits, checks it, and then expands it.

In the experiment, cultivation cut magic-state error about 40-fold compared with simple state injection, reaching a fidelity of 0.9999, or roughly one error in 10,000. The team also transferred (“grafted”) a cultivated state into a larger distance-5 surface code, the error-correcting scheme Google’s hardware relies on. Scientific American reports the run used 54 of Willow’s 105 physical qubits.

There are real caveats. Only about 8% of attempts passed the quality check; the rest were discarded. Breaking RSA-2048 encryption would need magic states that fail about once in 10 billion tries, and useful molecule simulations would need one in a million to one in 100 million, per Scientific American. A separate, not-yet-peer-reviewed arXiv preprint from researchers including Mikhail Lukin argues that cultivation’s practical costs can be higher once real-world measurement limits are included. New Scientist notes trapped-ion experiments have reached similar fidelities, though superconducting chips run faster.

What this means for you: Nothing changes for your encryption or devices today. If you follow quantum computing, this is a sign that fault-tolerant machines may need fewer qubits than once thought, but error rates still have to improve by several orders of magnitude before the big applications arrive.

Google Shows Magic State Cultivation Works on Its Willow Quantum Chip, Cutting Errors 40-Fold

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