Google · Friday, October 16, 2026
Google says a quantum trick cut errors about 40-fold
The File desk · Oct 16, 2026, 11:00 AM UTC
Status
Confirmed that Google published the post on Oct. 15, 2026, and that the company says the work is in Science. The error reduction and the fidelity figure are Google’s. This desk did not open the Science paper or rerun the experiment.
- Confirmed
Google Quantum AI said magic state cultivation works on its Willow processor and reduced errors about 40 times compared with states that were not cultivated.
- Confirmed
The company said it produced T-states with a logical fidelity of 99.99 percent, and that the work is published in Science.
- Partially confirmed
The claim that magic states have historically taken up to about 95 percent of a machine’s capacity is Google’s account of earlier estimates. This desk did not open those papers.
Google said Thursday that a method called magic state cultivation works on its Willow quantum processor and cut errors about 40 times compared with states made the old way. The company said the special states it produced were correct 99.99 percent of the time, and that the result is published in Science. Those figures are Google’s. This desk did not open the journal article.
The post is dated Oct. 15, 2026. The byline is Emma Rosenfeld, a research scientist, and Craig Gidney, a quantum software engineer, both at Google Quantum AI.
A magic state is a prepared quantum state that lets a machine run the operations it needs to go beyond what an ordinary computer can do. Google says making clean ones has been expensive. It says some estimates put as much as 95 percent of a quantum computer’s capacity on that job. That 95 percent figure is the company’s description of earlier estimates.
The method, Google says, was set out in a 2024 paper by Gidney, Noah Shutty, and Cody Jones. On Willow, the company says the protocol cut errors about 40-fold relative to uncultivated states and produced T-states at 99.99 percent logical fidelity. It also says the team showed it can move a purified state from one error-correcting code to another inside the same chip.
Google says the demonstration still has to be done at a larger scale before it is practical, and that technical problems remain.
This story does not grade the experiment. The numbers are what Google printed, and the Science paper was not opened.
What is still unknown or disputed
- The Science article was not opened. Publication in Science is Google’s statement.
- This desk did not check the 2024 theory paper or the historical estimates Google cites.
- “About 40 times” and “99.99 percent” are the company’s figures.
Primary sources
Every claim in this story is drawn from the documents below. If a fetch failed, that is recorded on the card.
Source 1
Bringing the magic: Google breaks open a bottleneck in quantum computing
Google · October 15, 2026
Google Quantum AI said magic state cultivation works on the Willow processor, reducing errors about 40 times compared with uncultivated states, and that it got T-states with a logical fidelity of 99.99 percent. The company said the work is published in Science. Authors: Emma Rosenfeld and Craig Gidney.
https://blog.google/innovation-and-ai/models-and-research/quantum-computing/magic-state-cultivation-quantum-computing/