MilestoneError correctionConfirmed

Google shows a larger error-correcting code can make fewer errors

Jul 13, 2022

Google Quantum AI reports that a logical qubit (an error-protected qubit built from many physical ones) using 49 physical qubits made slightly fewer errors than the average of smaller codes using 17. Google says no quantum computing platform had shown this before.

Why it matters

Error correction only helps if adding qubits to a code lowers the error rate; this experiment showed that trend on real hardware, although the improvement was small.

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Google's Willow chip shows errors can shrink as qubits grow (Dec 9, 2024)

Sources (4)

arXiv (Google Quantum AI) Suppressing quantum errors by scaling a surface code logical qubit
Primary sourceJul 13, 2022

“We find our distance-5 surface code logical qubit modestly outperforms an ensemble of distance-3 logical qubits on average, both in terms of logical error probability over 25 cycles and logical error per cycle”
Nature Suppressing quantum errors by scaling a surface code logical qubit
Primary sourceFeb 22, 2023

“We find that our distance-5 surface code logical qubit modestly outperforms an ensemble of distance-3 logical qubits on average, in terms of both logical error probability over 25 cycles and logical error per cycle”
Google Research Blog Suppressing quantum errors by scaling a surface code logical qubit
Primary sourceFeb 22, 2023

“To that end, we use a particular error-correcting code called a surface code and show for the first time that increasing the size of the code decreases the error rate of the logical qubit. A first-ever for any quantum computing platform, this was achieved by painstakingly mitigating many error sources as we scaled from 17 to 49 physical qubits.”
The Register Google claims milestone in quantum error correction
Independent coverageFeb 22, 2023

“A team at Google Quantum AI said it has demonstrated that a method of quantum error correction called surface codes can exhibit lower error rates as larger surface codes are employed.”

Added Oct 15, 2026 · Updated Oct 27, 2026. Spotted an error? Tell us and we will review it.

Google shows a larger error-correcting code can make fewer errors

Why it matters

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