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Google says it has achieved a huge breakthrough in computer science known as “quantum supremacy,” a feat heralding the potential dawn of a new computing era—one that could, in time, yield everything from better drugs and batteries to the unraveling of seemingly intractable mysteries of the universe.

The tech giant made the announcement in a paper published Wednesday in the 150th anniversary issue of the science journal Nature. Google’s assertion marks the first time researchers have claimed that a quantum computer—a device that exploits weird, quantum mechanical properties such as “superposition” and “entanglement”—has performed calculations no ordinary computer can complete.

The achievement, if it holds up to scrutiny, represents the consummation of decades of theorization and research. Drawing on a historical analogy, some scientists have compared the achievement to the first manned flight by the Wright brothers.

Sundar Pichai, Google’s CEO, called the event “the ‘hello world’ moment we’ve been waiting for—the most meaningful milestone to date in the quest to make quantum computing a reality.” He added, qualifying, that “we have a long way to go between today’s lab experiments and tomorrow’s practical applications.”

Hartmut Neven, engineering director for the Google AI Quantum team which conducted the research, said the day marks “a major milestone in quantum computing research that opens up new possibilities for this technology.”

“With the first quantum computation that cannot reasonably be emulated on a classical computer, we have opened up a new realm of computing to be explored,” commented John Martinis and Sergio Boxio, Google’s chief quantum scientists.

News of the milestone had leaked last month when an early version of the research paper had been inadvertently published on the website of NASA.gov, a collaborator on the project. At the time, Google declined to confirm the paper’s authenticity.

Google’s experiment involved running a series of calculations on a quantum computer called Sycamore, a device bearing 53 functional “qubits,” the quantum equivalent of classical computers’ bits. The team says its calculation, which simulated patterns of random numbers produced by a quantum circuit, took three minutes and 20 seconds to complete instead of the thousands of years it would have taken the world’s most powerful supercomputer, an IBM-designed machine called Summit.

The announcement comes mere days after scientists at IBM rejected Google’s quantum supremacy claims. That analysis was done based on the leaked version of Google’s research paper.

IBM, a rival to Google in quantum computing, argued in a blog post that the calculation in question could, theoretically, have run on Summit in a fraction of the time Google claimed. IBM researchers said that it would have taken a mere 2.5 days versus 10,000 years—still longer than Sycamore, but drastically shorter than Google said.

“This threshold”—quantum supremacy—”has not been met,” the IBM scientists declared, though they did not perform the proposed calculation.

Google was not deterred by IBM’s criticism. A Google spokesperson told Fortune, “We’ve already peeled away from classical computers, onto a totally different trajectory.” The spokesperson added, “We welcome proposals to advance simulation techniques, though it’s crucial to test them on an actual supercomputer, as we have. “

IBM has long objected to the concept of quantum supremacy, arguing that it encourages too much hype as well as the pursuit of niche, specialized stunts that have no practical use. Google scientists Martinis and Boxio counter that their research “has already been working on near-term applications, including quantum physics simulation and quantum chemistry, as well as new applications in generative machine learning, among other areas.”

Scott Aaronson, a quantum theorist at the University of Texas at Austin who peer reviewed Google’s paper, said that in spite of IBM’s criticism, he would still acknowledge Google’s achievement. Since Google’s quantum computer takes fractions of a second to run hundreds of simulations when IBM’s supercomputer takes days, “by my calculation there’s still a quantum speedup by a factor of about 10 million in wall clock-time,” Aaronson wrote in an email to Fortune. “By any reasonable definition, I’d say that this is still quantum supremacy.”

“This is a great achievement we should celebrate,” says Umesh Vazirani, a professor at the University of California at Berkeley. “They’ve put a huge amount of work into this—it’s a tour de force, experimentally, that they’ve carried out.”

Vazirani adds that his team and others will be testing—and seeking either to validate or refute—Google’s results in the months to come. “We are still trying to understand their robustness,” he said.

With today’s news, the rivalry between Google and IBM will only grow. Scientists at both companies are locked in a race to build the world’s first truly fault-tolerant quantum computer, which could take additional years to pull off. Once that’s achieved, it opens the door to all manner of business and scientific pursuits.

“Such a device promises a number of valuable applications,” Google’s Martinis and Boxio said of a fault-tolerant quantum computer. “For example, we can envision quantum computing helping to design new materials—lightweight batteries for cars and airplanes, new catalysts that can produce fertilizer more efficiently (a process that today produces over 2% of the world’s carbon emissions), and more effective medicines.”

It’s Official: Google Claims ‘Quantum Supremacy’

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