Prominent work on the borders of quantum physics by Montreal professor Gilles Brassard wins largest science award in the world

University of Montreal professor Gilles Brassard received the largest science award in the world.Amelie Philibert / University of Montreal

Gilles Brassard, a computer scientist at the University of Montreal who has made a fundamental contribution to the field of quantum cryptography, received the Breakthrough Prize for Fundamental Physics, the largest scientific award in the world.

In an announcement by the Breakthrough Prize Foundation on Thursday, prof. Brassard was named co-winner of the $ 3 million award, along with his longtime collaborator, Charles Bennett, a researcher with IBM in the United States. Oxford University physicist David Deutsch and Peter Shor, a professor of applied mathematics at the Massachusetts Institute of Technology, are also co-winners for separate contributions in the field of quantum information.

Their collective discoveries are the result of a once esoteric exploration that began in the early 1980s and transformed into an ambitious and potentially revolutionary quest to develop quantum computers on a commercial scale.

The award is just the latest for Dr. Brassard, who won the prestigious Wolf Prize in physics in 2018.

Hi and Dr. Bennett is considered a likely contender for a future Nobel Prize for devising quantum key distribution, a practical way in which information can be securely sent and decrypted using a digital key linked to the quantum properties of a system. physicist. Any attempt to intercept the transaction would disrupt the quantum nature of the key, so it could no longer be used.

Prof. dr. Deutsch is known for elaborating on how the principles of computing work when the digital bits on which a calculation is based are subject to the strange rules of quantum physics. In the 1990s, Dr. Shor, showed that if a quantum computer could work, it would undermine RSA cryptography, the conventional method by which much of the world’s digital information, including financial transactions, is kept private.

The Breakthrough Award is awarded annually for achievements in physics, mathematics and life sciences. It was founded in 2012 by Russian-Israeli entrepreneur Yuri Milner and is supported by Meta Mark Zuckerberg and Google co-founder Sergey Brin, among other Silicon Valley luminaries.

Robert Myers, director of the Perimeter Institute for Theoretical Physics in Waterloo, Ontario, called this year’s winners “a wonderful choice” for the award.

“I think he recognizes something that is growing and growing,” Dr. Myers said. “These are the people who laid the foundation for quantum information.”

for prof. Brassard, the journey began in the Caribbean Sea. It was 1979 and he had just taken a place at the University of Montreal after completing his PhD. At a conference in Puerto Rico where he was to give a talk on cryptography, he went for a swim and was approached by a stranger with an unlikely conversation starter.

“He swims up to me and starts telling me he knows how to use quantum theory to create banknotes that are impossible to counterfeit,” said the prof. Brassard said. “So I had to listen and I realized what he was saying was interesting, but impractical and useless.”

The stranger was Dr. Bennett and the conversation stimulated Prof. dr. Brassard to see how the idea could be made useful, though still impractical, as he continued his swim. Soon after, the two were exchanging ideas and collaborating on what would become the basis for a science of quantum cryptography.

As a computer scientist, prof. Brassard was not deeply attached to fundamental physics, especially the hard-to-interpret implications of quantum theory, which seemed to allow astonishing possibilities such as particles existing in more than one place at once until they are measured.

“I had never taken a quantum theory class before,” he said, “but when Bennett explained these things to me, I was totally seduced by how good it is.”

for prof. Deutsch, the attraction was in the opposite direction. As a physicist, he was exploring issues related to the nature of reality, including the idea that some of the contradictions in quantum theory can be explained if there are multiple universes, each representing a different outcome, such as a path a particle can take.

Once again it was Dr. Bennett who provided the momentum. After a conversation with the IBM researcher at a party, Dr. Deutch decided to look at how computers work in a quantum world. As he and others would soon realize, it meant that the bits of information – the ones and zeros that underlie conventional computer calculations – would be replaced by “qubits,” which have a certain probability of being either one or zero.

When exploited together, qubits can efficiently perform multiple computations, using the same hardware, at the same time as a conventional computer can perform a single operation. This can dramatically speed up some types of computations, including those that are critical to data encryption today.

dr. Deutsch said he was happy to accept the idea that a quantum computer achieves its power by working in multiple universes at the same time. However, it is also possible that a deeper understanding of quantum physics will one day provide a better interpretation.

The problem, he said, is that such an interpretation “will be even stranger than what we have now.”

Since the recipients began their award-winning work, technical advances have moved quantum computers into the realm of the possible and are getting closer and closer to being practical.

dr. Brassard said the field is busier than ever, fueled in part by the realization that the data world needs an urgent response to the impending obsolescence of today’s cryptographic systems.

When asked what he intended to do with his share of the prize money, Dr. Brassard, 67, said he hadn’t thought about it yet, “but it’s not for retirement.”

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