A quantum computing system's perfect randomness could keep your secrets safe - Scientific American

May 27, 20263 min readA quantum computing system's perfect randomness could keep your secrets safeGenerating and confirming the randomness of qubits could lead to breakthroughs in computer data encryptionBy Adam Kovac edited by Claire CameronETH ZurichJoin Our Community of Science Lovers!The orderly flow of information around the globe depends a lot on security, and at the heart of that security is randomness.Modern-day encryption relies on unpredictability to avoid being cracked, and the most powerful form of unpredictability is randomness. And in a new study, researchers describe a new way to amplify that randomness.Random number generators have been around for years, but they often have subtle imperfections that cause patterns to emerge. And even powerful computers are saddled with this liability purely because they use traditional transistors to generate the binary code—ones and zeroes—that enables computers to store data and make calculations.If you're enjoying this article, consider supporting our award-winning journalism by subscribing. By purchasing a subscription you are helping to ensure the future of impactful stories about the discoveries and ideas shaping our world today.“Any conventional electronic device like a phone or a computer is completely deterministic so it's actually very difficult for a computer or any other electronic device to generate a random value,” says Renato Renner, a physics professor at Switzerland’s Swiss Federal Institute of Technology Zurich and member of the research team. “It cannot just toss a coin, because everything that goes on in the scale of the logic is basically completely predictable.”While these numbers may seem random at first glance, a quantum computer would be able to recognize even the most obscure patterns and thus, crack the code.“Unpredictability is very important, because that's what the adversary would do to attack it—to just try to predict parts of that password, or even the full password, or parts of the key,” says Renner.That’s where the new system comes in. Qubits, the basic component of information in a quantum computer, don’t exist in a binary. Instead, they have an infinite number of states in which they can exist, only collapsing into a single state when the qubit’s position is measured. In a paper published in Nature on Wednesday, Renner and his colleagues describe how a two qubit system could generate true randomness.The scientists entangled two qubits kept at near absolute zero temperatures at the opposing ends of a 30-meter long tube. When the two qubits are entangled, they share the same positioning—in other words, if you measure both, you’ll get the same output. The long tube was necessary to ensure enough physical separation so that no outside variables could be biasing the results, Renner says.“To really be sure that it's not predictable, I need to have a process where I'm really sure that this process is not described by classical physics,” says Renner.In one experiment, a photo of a sheep was run through the system, and its pixels were translated into randomness. The resulting mess of colors and splotches would be impossible to put back together, even using a quantum computer, according to the research.To further test their system, the team ran what’s known as a Bell test, which analyzes a quantum system for any hints it might be affected by classical physics.“Our setup is one that allows you to run many Bell tests with good quality and at a fast rate,” Renner's colleague and study co-author Andreas Wallraff says. “For our experiment, we ran about a billion and a half of these Bell tests to create certifiably random outcomes that then are used in an algorithm that Renato and his team had developed to create this certified randomness.”While previous experiments have been able to generate randomness, Renner said the inclusion of a second qubit as a verification measure is new. That development enhances trust, another essential component to solid encryption.Commercially available quantum computers are still a long way off, but the real-world implications of Renner and Wallraff’s work is relevant now. Renner notes that there’s an entire Wikipedia page dedicated to hacks that were only possible due to imperfect cryptographic randomness.“This is the problem we solve, which is a current problem, not only a problem in the post-quantum cryptography era," he says, "but of course it will remain a problem.”“I think cryptography will always rely on good randomness, independently of whether it's now cryptography against conventional adversaries or future quantum adversaries,” he adds.Adam Kovac is a breaking news reporter at Scientific American.If you enjoyed this article, I’d like to ask for your support. 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