Runner-Up

Gilles Brassard

Founding Director, Institut transdisciplinaire d’informatique quantique (INTRIQ)

Canada Research Chair in Quantum Information Processing

Université de Montréal

Gilles Brassard

March 16, 2009 – A century after his Annus Mirabilis, Albert Einstein would be impressed. His 1905 pioneering work on quantum mechanics, possibly the most spectacular scientific theory of all time, is being taken to new heights by Gilles Brassard of the Université de Montréal. Prof. Brassard is applying that theory to information processing, and his groundbreaking research is set to be just as revolutionary for 21st-century computer science as Einstein’s work was for 20th-century physics.

The founder of quantum information processing in Canada, and one of its earliest pioneers worldwide, Prof. Brassard has been expanding the frontiers of knowledge for three decades. He explores novel uses of quantum mechanics to enhance information-processing capabilities. His achievements cover the full range of research from pure theory to concrete experiments.

His two most celebrated breakthroughs are the invention of quantum cryptography and quantum teleportation, which may evoke images of Star Trek, but are strictly based on established science.

Until the late 1970s, the theory and practice of computer science and information theory were firmly rooted in the classical physics of Isaac Newton. Even though quantum mechanics had played a major role in technological improvements, such as the invention of the transistor, electronic computers have remained essentially classical creatures.

That all started to change at a beach resort in San Juan, Puerto Rico, leading to a completely new information-processing landscape. In 1979, a stranger unexpectedly swam up to Prof. Brassard and began explaining how to use quantum mechanics to design banknotes that are impossible to counterfeit.

"This was probably the most bizarre, and certainly the most magical moment in my professional life," Prof. Brassard recalls. The stranger was Charles H. Bennett, a physicist at IBM Research, who was talking about an unpublished theoretical idea of his friend Stephen Wiesner from almost 10 years earlier. After swimming back ashore, they worked out the main ideas for their first joint paper, in which the term "quantum cryptography" was coined. Little did they suspect on that day that they would come to share the Rank Prize in Optoelectronics with Dr. Wiesner more than a quarter-century later. Thus was born a wonderful collaboration that would also spin out quantum teleportation, entanglement distillation and many other wonders.

Quantum cryptography makes it possible to communicate in perfect secrecy under the nose of an eavesdropper whose technological and computational power is restricted by nothing more than the laws of physics. This is achieved with no need for a lengthy, shared secret key, as was previously required. To counter the scepticism of the international research community, the collaborators built a working prototype in 1989. On the 10th anniversary of the San Juan encounter, they made history with the world’s first transmission whose secrecy was guaranteed by quantum mechanics.

The February 2003 issue of Technology Review (published by MIT) highlighted quantum cryptography as one of the "10 emerging technologies that will change the world."

Quantum entanglement, which was theoretically discovered in 1935 by Einstein, Boris Podolsky and Nathan Rosen, is perhaps the most strikingly non-classical of all quantum phenomena. In collaboration with Bennett and other colleagues such as Claude Crépeau (now at McGill University), Prof. Brassard has discovered a completely unexpected way to harness entanglement for the transmission of quantum information through a classical channel. The result was quantum teleportation, invented the morning after a brainstorming session held in Prof. Brassard’s office. According to Thomson Scientific’s ISI Web of Knowledge, the resulting scientific article has attracted an average of nearly two citations every day in the past year. The theory of quantum teleportation was chosen by Discover magazine as being among the world’s top science stories of 1993.

Quantum entanglement also enables the accomplishment of some distributed tasks with a vastly reduced communication cost. "In extreme cases, we can have non-communicating participants react jointly to private stimuli in a way that would be classically impossible. This is the mysterious realm of pseudo-telepathy, a term coined by my colleague Alain Tapp," says Prof. Brassard.

Although full-scale quantum computers have not yet been built, in principle they can perform exponentially more parallel computation in a single piece of hardware than would be possible with a classical approach. It follows that more computation could occur in one thousand quantum bits than would be possible with a classical computer even if every elementary particle in the known universe could be harnessed as a data processing unit.

"Quantum computers have the potential to bring to their knees most classical cryptographic schemes currently used to protect transactions on the Internet, such as the transmission of credit card numbers," Prof. Brassard notes. "Fortunately, quantum cryptography fights back, fulfilling the cryptographer’s age-old dream of unconditional confidentiality in communications."

Among the most respected computer scientists in the world, Prof. Brassard has played a pivotal role in transforming quantum information processing from what appeared to be merely a fringe pursuit into an exciting and dynamic scientific research area vigorously pursued internationally. His influence continues to be felt through his discoveries, talks and the activities of his former students and postdoctoral fellows, eighteen of which have since become professors in various universities around the world.

Author of three books translated into eight languages and Editor-in-Chief of the Journal of Cryptology (1991-98), Prof. Brassard has given well over 200 invited lectures in more than two dozen countries on four continents. According to Google Scholar, his papers and books have been cited more than fifteen thousand times during his career. As part of the 50th anniversary celebration of Physical Review Letters, the American Physical Society has selected a series of "milestone Letters that made long-lived contributions to physics"; two of Prof. Brassard’s papers were thus highlighted.

For his impact on the field, Prof. Brassard is the first Canadian to have been elevated to the rank of Fellow by the International Association for Cryptologic Research, a distinction shared by less than 20 people in the world. He is also a Fellow of the Royal Society of Canada and of the Canadian Institute for Advanced Research, and a foreign member of the Latvian Academy of Sciences. His many awards include an NSERC E.W.R. Steacie Memorial Fellowship, a Killam Research Fellowship and the Prix Marie-Victorin—which is the highest recognition given by the Government of Québec in the natural sciences and engineering.