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Google Quantum AI: Willow, Error Correction and Quantum Echoes

Updated | 4 min read | QUANTUM (QNT) community

Willow in plain English

Willow is a 105 qubit superconducting chip. The key result was error correction below threshold: as the team grew the size of an error correcting patch of qubits, the error rate went down instead of up. Before that, adding qubits tended to add noise. It is the first big step toward reliable logical qubits. See error correction and the surface code.

Quantum Echoes

In October 2025 a Nature paper described Quantum Echoes, an algorithm Google said produced a verifiable quantum advantage on Willow, meaning another quantum computer or an experiment could check the result. Google claimed it ran far faster than the best classical supercomputers on that task. Advantage claims are often challenged, so see supremacy vs advantage.

The security angle

Google researchers also published estimates that RSA-2048 might need under one million noisy qubits, far below earlier numbers. One report says a March 2026 Google advisory urged Bitcoin developers to finish migration by 2029, which we could not verify directly. See post quantum crypto.

What is not here yet

What to watch

New chips, more logical qubits, and papers on useful problems. Google talks appear at major events in the calendar.

The numbers behind Willow

Google unveiled Willow in December 2024. In the error correction experiment, the team built logical qubits from grids of physical qubits of growing size, and each step up cut the logical error rate by roughly half. Google also reported that on a standard benchmark called random circuit sampling, Willow finished in under five minutes a task it estimated would take a leading classical supercomputer an astronomically long time. That benchmark has no practical use, so read it as a hardware milestone. See quantum benchmarks explained and what sampling claims prove.

Quantum Echoes in more detail

The Nature paper was published on October 22, 2025. Coverage reports that Google said the experiment ran about 13,000 times faster on Willow than the best known classical approach on the Frontier supercomputer would, with the full classical calculation estimated at around 150 years. The algorithm measures how information spreads through a quantum system: run a sequence of operations, nudge one qubit, then reverse the sequence and compare. The result depends on subtle interference effects that are hard for classical computers to simulate.

In a companion demonstration with UC Berkeley, Google reported using the technique with nuclear magnetic resonance data on two molecules, one with 15 atoms and one with 28. This is an early step toward quantum computers helping to read molecular structure, and the molecules involved were small enough that classical methods can also handle them, so it is a proof of concept rather than a new capability for chemists. See why chemistry is quantum-hard.

What outside experts said

Science News reported that the result had not yet been checked on a second quantum computer when it appeared, and that a physicist at New York University noted a faster classical algorithm has not been ruled out. This pattern is familiar: earlier claims were followed by classical rebuttals, as in the supremacy rebuttal story. The honest summary is that Quantum Echoes is a strong, well documented result, and its lasting status depends on independent replication and on whether it leads to a useful application.

Status as of 2026-10-09

We checked for newer chip announcements and did not find a verified successor milestone beyond Willow and Quantum Echoes in the sources we could read. Google may have announced newer work, so check Google Quantum AI's own publications page. For comparison with a rival, see IBM's roadmap and the state of error correction in 2026.

Why it is exciting

Below-threshold scaling is the property every fault tolerant design needs. It means the path from today's chips to useful machines is no longer only a hope but a measured trend that engineers can push. Read the people behind it in the Neven and Gidney profiles, and the wider company map in Google Quantum AI software and roadmap. This is education, not investment advice, and it has no link to the QNT memecoin.

Sources and further reading

Reported as of 2026-10-09. Company roadmaps are targets and often slip. Check each company's own announcements.

Frequently asked questions

How many qubits does Willow have?

105 qubits.

What is below threshold error correction?

It means making the error correcting code bigger lowers the logical error rate, which is required for scaling.

What is Quantum Echoes?

An algorithm result published in Nature in October 2025 that Google described as a verifiable quantum advantage.

Can Willow break Bitcoin?

No. It is far too small. Breaking elliptic curve cryptography would need a much larger error corrected machine.

Is Quantum Echoes useful yet?

Not commercially. Google framed it as a step toward chemistry and materials applications, and the molecule demonstrations were small proofs of concept.

Has another lab confirmed Quantum Echoes?

At the time of early coverage it had not been replicated on a second quantum computer. Check for newer reports.

How fast did Google say it was?

Coverage reports about 13,000 times faster than the best classical approach on the Frontier supercomputer, according to Google.

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