The pioneers of quantum cryptography, recognized with the Frontiers of Knowledge Awards

In the 1980s, the chemical physicist, Charles Bennett, and the computer scientist, Gilles Brassard, invented quantum cryptography, enabling the encoding and transmission of messages, thus ensuring the physical inviolability of data communications. The relevance of this technology was revealed ten years later when the mathematician, Peter Shor, discovered that a hypothetical quantum computer would render the conventional cryptographic systems on which current Internet communication security and privacy depend effectively useless.

Their pioneering work has significantly contributed to the development of quantum computers, which deliver greater speed and scale than traditional computers when performing calculations, as well as to quantum systems of cryptography, which will be required to safeguard communications in the future. Their work, “spans multiple disciplines and brings together concepts from mathematics, physics and computer science, Their ideas are playing a key role in the development of quantum technologies for communication and computation,” the Frontiers of Knowledge Awards jury explained.

The origin of quantum cryptography

Quantum cryptography arose from findings in basic science, but in just a few decades it has given rise to a new technology seemingly on the cusp of a market explosion. When Bennett and Brassard began working together in 1979, this reality did not even enter the realm of possibility. Quantum physics and quantum computing were distinct fields of work, and research crossing between the two was minimal. By1984, Bennett and Brassard had produced a striking result: a cryptographic system that enabled the encoding and transmission of messages using the laws of quantum physics in order to prevent third parties from “listening” even should they have quantum resources at their disposal.

“Quantum information is a kind of information that is disturbed by observation and cannot be copied. Gilles Brassard and I realized that it could be used for the practical purpose of sending messages, in such a way that the sender and receiver could tell immediately whether anyone had listened to the message en route,” Bennett recounted after he learned of the recognition from the Frontiers of Knowledge Award. “And that, in essence, is quantum key distribution or quantum cryptography,” he concludes.

Shor discovered that the supposedly unsolvable problem on which classic cryptography is based — the factorization of large numbers — could indeed be addressed by a hypothetical quantum computer. The mathematician's contribution to the field carries his name: Shor's algorithm, and is one of the quantum algorithms that constitutes the computer language — still in the throes of development — of the quantum computers of the future. "When Shor discovered that if you could build a quantum computer, it would defeat certain cryptographic systems in widespread use, that stimulated a lot more research, because the cryptographers wanted to find more secure systems that were harder to break,” explains Bennett. “And at the same time other people wanted to build a better quantum computer to see what it could be used for besides code breaking.”

At present, quantum cryptography is one of the most advanced of all quantum technologies. The ongoing development of quantum computing, however, is viewed by the Frontier of Knowledge Award winners as a long term challenge, which will not immediately deliver on the high expectations that have followed the first prototypes developed by the big tech companies. Still, they do not doubt the future potential of quantum computers. According to Brassard, “the 19th century was the era of steam power, the 20th century was the era of information, and the 21st century will go down in history as the quantum age, the age in which quantum technologies dominate all the changes occurring in society, in a way we cannot yet foresee.”

Commenting on his expectations, Shor says, “it will be 5 or 10 years before a quantum computer can do anything approaching useful," but he is convinced that, with time, revolutionary applications will be achieved with these machines, for example in the field of biomedicine, assisting the development of new pharmaceuticals: "At the moment, it takes enormous amounts of computer time to simulate the behavior of molecules, but quantum computers could achieve that, and help design new drugs.”