E-Paper
Quantum advance paves way for ‘un-hackable’ digital future
The new research has shown that it is possible to harness the quantum randomness to generate numbers that are truly reliable or certified
Scientists led by a senior quantum physicist at the Raman Research Institute (RRI) in Bengaluru have shown that true digital security is possible. The team of researchers has generated secure, certified random numbers by working on a single unit of quantum information. This key step, which does away with earlier complex setups, opens up what they called “a path toward un-hackable digital security”.
Random numbers are a sequence of numbers that is not predictable. Outside of the lab, they are especially important in the domain of secure communications, for instance in the generation of OTP in banking services or keeping data secure in strategic sectors. The OTP you receive, the number you type in a two-factor authentication system, and end-to-end encryption on your WhatsApp chats all depend on this randomness.
Actual randomness, however, cannot be generated by classical computers alone. In theory, these random numbers can be “guessed” by hackers because they are generated by a predictable set of rules.
The key lies in the quantum world, where everything happens randomly in strange ways that defy predictability. The new research has shown that it is possible to harness the quantum randomness to generate numbers that are truly reliable or certified.
This is called certified quantum randomness. Certified randomness has been achieved earlier, but the methods used were complicated and prone to loopholes on existing quantum computers. The RRI-led researchers have simplified the process by using a new approach. They moved from one mathematical concept (called the Bell’s inequality) to another (Leggett-Garg inequality). These inequalities are used to test the predictions of quantum mechanics.
Any scheme to certify random numbers needs to be independent of the device used because a device-dependent scheme would be vulnerable to possible tampering by malicious parties and also device imperfection like ageing, said Professor Urbasi Sinha, head of RRI’s Quantum Information and Computing (QuIC) lab. She was one of the winners of the Shanti Swarup Bhatnagar Prize for Physics in 2024.
“That is why we need device-independent certification. Bell’s inequality is one such device independent certification, but to do this in a foolproof way we need a large spatial separation between two involved parties,” Sinha told HT.
The new method depends on correlations in time (temporal) rather than spatial. “This can be achieved by a single quantum particle moving in time. Instead of Bell’s inequality, the certification is done by the Leggett Garg inequality which captures temporal correlations,” Sinha said.
Her research, in collaboration with researchers at Indian Institute of Science (IISc) in Bengaluru and the University of Calgary in Canada, has been published in the journal Frontiers in Quantum Science and Technology. It is the culmination of efforts over a number of years that have resulted in a series of papers.
The foundation was laid with a landmark experiment by RRI researchers in 2022. It addressed a fundamental question: is the world predictable under the laws of classical physics or is it governed by the random tenets of quantum mechanics? Using single particles of light (photons) and testing their correlations in time, the researchers decisively proved quantum mechanics right, closing every possible loophole that could have cast doubt on it.
In 2024, they used this loophole-free photonic architecture to develop a device that could generate random numbers certified by quantum mechanics. The random bits generated were nearly a million units strong (the digital equivalent of a million coin flips), and the fundamental physics was now ready for technological advancements.
The latest research takes a step towards such advancements. It shows that certified quantum randomness can be achieved on a general-purpose quantum computer available through the cloud. Earlier demonstrations had used an approach that was practical only within specialised laboratories.
“We had already shown that certified random numbers could be generated using our quantum optics equipment. In the present work, we experimentally show how existing quantum computers can be used to generate certified randomness, overcoming the existing noise barrier in these machines. This provides not only a practical use case for currently available commercial quantum computers, but also a fundamental benchmark towards testing future such devices from India and beyond,” Sinha said.
