In a breakthrough that sounds almost philosophical, researchers at ETH Zurich have done what seemed impossible: they've created truly perfect randomness using quantum physics. For decades, cryptographers and mathematicians have grappled with a stubborn problem—even the best random number generators contain tiny, systematic errors that make some numbers appear slightly more often than others. In ordinary applications, this barely matters. But in cryptography, where the security of your bank account or your encrypted messages depends on genuine unpredictability, even microscopic bias can crack the entire system open. Now, Renato Renner and Andreas Wallraff's teams at ETH Zurich have not only solved this ancient puzzle but proved it in a way that's mathematically beyond question.
The solution required quantum physics at its most elegant—and most complicated. Wallraff's team built an experimental setup using two superconducting chips, each representing a quantum bit, or qubit, cooled down to nearly absolute zero. These chips sit at opposite ends of a 30-meter-long chilled tube, connected by microwave photons that create quantum entanglement between them. When they measure one qubit randomly yielding a "0" or "1," that measurement instantly influences the outcome of the second qubit, no matter the distance. Crucially, that 30 meters ensures that even light itself cannot travel between the chips during measurement, guaranteeing that the randomness cannot be compromised by hidden information flowing between them.
The elegance lies in what happens next. Rather than trying to create perfect randomness from scratch, Wallraff and Renner did something more clever: they took imperfect randomness—generated by an ordinary random number generator—and fed it into their quantum setup to determine which type of measurement to perform on each qubit. Then Renner's team applied a special algorithm that amplified the randomness of the measurement results. The output was a sequence of zeros and ones that is provably, certifiably perfect. "The resulting sequence of zeros and ones is now really perfectly random, and we can even certify that," Renner explained. He describes the achievement as crossing a ridge: for the first time, they created random numbers that will remain perfectly random forever, no matter what analytical methods future scientists devise to test them.
The implications ripple across digital security. Wallraff suggests this work could become an "atomic clock for randomness"—a physically guaranteed reference point that other systems can trust absolutely. Cryptographic encryption is only as strong as the randomness underlying it; weak randomness makes even sophisticated encryption collapse. This discovery opens doors to far more robust encryption of sensitive communications, digital identities, and blockchain applications. As quantum computing advances, the stakes grow higher still: quantum-secure communication systems will depend on randomness certified at this level to remain unbreakable.
Their results, published in Nature, represent a watershed moment. For the first time, humanity has a way not just to create perfect randomness, but to prove mathematically that it is perfect—a turning point in humanity's long struggle against chaos and predictability. The work was led by Anatoly Kulikov and published in Nature in 2026.