In a paper published this week in Nature—but inadvertently leaked last month on a NASA Web site—Google engineers describe a benchmark experiment they used to demonstrate supremacy. Their program, run on more than 50 qubits, checks the output of a quantum random-number generator. Some critics have complained this is a contrived problem with a limited real-world application, says Hartmut Neven, manager of Google’s Quantum Artificial Intelligence Lab. “Sputnik didn’t do much either,” Neven said during a press event at the Goleta facility. “It circled the Earth. Yet it was the start of the space age.”

David Awschalom, a condensed matter physicist specializing in quantum-information engineering at the University of Chicago, who was not part of the research, agrees that the program solved a very particular problem and adds that Google cannot claim it has a universal quantum computer. Such an achievement would require perhaps a million qubits, he says, and lies many years in the future. But he believes the company’s team has reached an important milestone that offers other scientists real results to build on. “I’m very excited about this,” Awschalom says. “This type of result offers a very meaningful data point.”

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Image: Array of Google’s Sycamore quantum-computing chips being prepared for preliminary electrical testing. Credit: Google