Practical quantum computers may still lie some way in the future, but researchers are already getting excited about the next leap: the “quantum internet.” This is a still-theoretical way to connect quantum computers to one another, one day allowing people to compute and exchange data across distant devices. And there’s already a lively debate about how involved the government should get in its development. Much like the classical internet of zeroes and ones, a quantum internet is based on the premise that you can do a lot more over a network linked with other computers and data systems than you can when limited to the processing power of a single machine — even if that machine has the unusual powers of a quantum computer. Scientists think future quantum communication networks will be especially useful for solving complex problems in the fields of finance, medicine, and scientific research that quantum computers may struggle with alone. They also promise nearly unbreakable encryption, making it essentially impossible to intercept or eavesdrop on messages encoded in quantum states. The challenge — as with quantum computers themselves — is in achieving all this while in a system governed by the weird laws of quantum mechanics. No one has been able to successfully develop a stable quantum network on a large scale. That’s partly because a key technology for sustaining the connection, the quantum repeater, does not yet exist. Repeaters are used in regular computer networks to amplify signals across long distances; quantum repeaters would need to do the same without disrupting the qubits, the basic units of information in a quantum computer. To get around the lack of a quantum repeater, researchers around the world are building quantum networks as testbeds to send information across distances of dozens of kilometers. In a major sign of progress earlier this month, groups at Harvard University and the University of Science and Technology of China were able to separately demonstrate the subatomic phenomenon known as quantum entanglement over existing optical fibers in real cities. Nature declared the experiments, together with a third posted in a preprint last month, “the most advanced demonstrations so far” of the technology needed for a quantum internet. “From the center of a city, you cover a lot of people and a lot of businesses, meaning that you can already think about practical quantum networks that don’t need a repeater,” said David Awschalom, who leads the Chicago Quantum Exchange and a proposal for a federal quantum hub. “It may not go city-to-city, but within metropolitan regions, you can begin to deploy the technology, and that alone for financial institutions and lots of applications would be fantastic.” On the policy front, however, quantum proponents are hitting some friction. For decades, the government has funded the underlying science of quantum mechanics. Now, those same sources of funding are facing shortfalls, as quantum needs help to transition from making scientific discoveries to developing applications that could finally bring the technology into the mainstream. Jane Bambauer, a University of Florida law professor who has analyzed the state of quantum policy, said that the Harvard study is an important development, but still very early. Despite the rise of quantum-specific startups and more existing companies shifting into the space, the private sector is not expected to make returns on quantum anytime soon, meaning it’s a riskier bet for investors and thus more dependent on federal research money. “It really only becomes a viable business strategy to invest later in the pipeline when you're closer to getting a commercial product,” said Bambauer. “And so we need the public purse to invest, as we always have.” Awschalom makes the case that for a technology like quantum, the government has a hugely important role in proactively addressing larger issues such as workforce development and setting standards: “you hit a critical point, and the markets just take off and you need to be ready.” It’s hard enough to get consistent attention from Washington for any technology that takes years to develop, but Congress lately has really struggled with following through on pledged funding for early-stage research. House Science Chair Frank Lucas (R-Okla.) drew attention to the problem in a hearing last week, stressing that while “innovation thrives on stable, predictable funding,” the past few years have created a “feast-and-famine situation” for agencies like the National Science Foundation with long histories of investing in quantum research. Since November, Lucas and the committee’s top Democrat, California Rep. Zoe Lofgren, have pushed for reauthorizing the National Quantum Initiative Act (NQIA), which will set national scientific, economic and security priorities for quantum over the next five years. NSF Director Sethuraman Panchanathan told them that this year’s budget request represents an incremental $30 million increase for quantum information science from fiscal year 2023, which is “nowhere near where the appetite is in the nation.” Bambauer argued that it’s true some of the quantum algorithms scientists have in mind may not pan out or be practical, but there is enough of a possibility that the government should take the bet. The long-term gains could have payouts in simulating unsolved problems and discovering unique materials. “Even if there's just a small chance of the quantum computing programs that we hope to develop working,” she said, “It’s actually a pretty low cost investment.”
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