Google Just Cut a Major Quantum Computing Error Rate by 40 Times
Google's quantum lab just cleared a barrier that has quietly set the ceiling on how powerful a quantum computer can ever get, and the implications reach well beyond a single research paper.
Google Quantum AI published “Magic state cultivation on a superconducting quantum processor” in the journal Science on October 15, 2026. The paper is the first hardware demonstration of a technique that cut errors 40-fold compared with states prepared without it.
Class A shares of Alphabet (NASDAQ:GOOG | GOOG Price Prediction, NASDAQ:GOOGL) rose 0.45% that day to close at $349.22, which valued the company at $4.27 trillion. The small move reflects how a stock this large trades on search, cloud, and AI, and investors treated the paper as good science with a distant return.
A lab result like this changes very little. It strengthens a long-term research effort that Alphabet can fund with its own profits.
What Google Demonstrated on Willow
The experiment ran on Google’s Willow processor. It produced T-states, a type of magic state, at 99.99% logical fidelity, which means an error rate of 0.0001 or less.
Google researchers Craig Gidney, Noah Shutty, and Cody Jones developed the method in 2024. It places an imperfect state in a small chip region. It checks the state with measurements, discards failures, and extends the survivors into a larger error-correcting code.
Only 8% of attempts passed the filter. Throwing away most attempts is how the method works, because it gives up volume to get quality.
Alphabet CEO Sundar Pichai reacted on X that day. He wrote: “Some magical progress towards “magic state” in quantum!”
Why Magic States Set the Size of a Quantum Computer
Complex quantum calculations need magic states. Each one can be used only once, so the machine has to keep making new ones. Some estimates say up to 95% of a quantum computer’s capacity could go to producing them.
Without a cheap, reliable supply of magic states, a quantum computer can only run calculations an ordinary computer already handles, and making them more cheaply reduces how large a machine you would need to build.
How Much Quantum Is Worth to Alphabet Shareholders
Alphabet does not report quantum as its own division. The closest line is Other Bets, which brought in $382 million in the second quarter of fiscal 2026. Total revenue that quarter was $119.8 billion.
Google Cloud brought in $24.77 billion in the same quarter, up 82%, and Cloud is what moves the stock. Google disclosed no revenue, customers, or timeline tied to the quantum result.
The quantum lab is paid for by a business that earned $40.77 billion in operating income in that one quarter. Smaller quantum companies depend on investors staying interested enough to fund them.
There’s still a bottleneck.
Magic states are still a constraint. Cultivation now has to work at a much larger scale, inside a machine running a useful calculation, before it changes what quantum hardware can do.
Other large technology companies and smaller listed quantum firms have their own error-correction plans; Google leads in one technique, and the field is competitive.
What Drives Alphabet’s Valuation From Here
Alphabet’s investment case rests on the core business, and quantum is a long-term research effort that shareholders get at no added cost.
The shares are up 11.79% so far in 2026 and 39.48% over the past year. They trade at about 16 times trailing earnings. But that multiple looks cheaper than it really is because second-quarter net income included a $99.03 billion gain on equity securities.
The main risk is spending. Second-quarter capital spending, the money spent on data centers and equipment, reached $44.92 billion, and free cash flow, the cash left after that spending, was negative $5.86 billion. That expansion also feeds a long list of suppliers in power, cooling, and networking (we featured seven of them in a free report on the AI infrastructure trade).
The thing to check is Cloud growth in the third-quarter earnings report. If growth stays near the second quarter’s pace, the case for the stock holds. A sharp slowdown would hurt the stock far more than a quantum paper could help it. On the quantum side, look for a follow-up paper showing cultivation supplying a logical computation at larger scale.
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Omor Ibne Ehsan is a writer at 24/7 Wall St. He is a self-taught investor with a focus on growth, cyclical, and dividend equities that have strong fundamentals, value, and long-term potential. He also has an interest in high-risk, high-reward investments such as penny stocks.
