9 June 2020 Tom Mallah
Dave Touchette

A taste for quantum computing

Prof. Dave Touchette

Photo : Provided

For many, the buzz around quantum computing is a fairly recent development but Dave Touchette’s passion for this field is nothing new. For over 10 years, he has been pursuing research in quantum information and communication.

When we ask what is it about his emerging field that fascinates him most, Prof. Touchette quickly answers: “It’s still new. There are a lot of questions to study, new subfields that are emerging. It’s exciting to be at the frontier of research. Tackling problems that we don’t have any hope of solving on conventional computers opens up the potential for problems we thought were beyond our reach.”

Originally from Saint-Jean Baptiste in Montérégie, Prof. Touchette’s return to Québec happened rather naturally following his postdoctorate at the University of Waterloo. In August 2019, he became the first professor in the Department of Computer Science to join Institut quantique (IQ).

One thing leads to another

Dave Touchette got his first taste of quantum computing during his undergraduate degree at Mcgill University. At the time, he was working on his end-of-studies project: “I learned a lot about information theory then. I knew that overall it was in quantum computing that I wanted to pursue my studies, but I didn’t know exactly what aspect.”

At Université de Montréal, under the supervision of Professors Gilles Brassard and Alain Tapp, he developed his expertise in information theory, communication theory and quantum computing: “Information theory is often very useful when communicating over a noisy channel or if we want to compress data. If we do quantum processing, does that help us in any way? That’s what I focused on during my PhD, which opened up a multitude of potential research avenues.”

The opportunity to do a postdoctoral presented itself at the University of Waterloo with Prof. Ashwin Nayak and Prof. Debbie Leung, two luminaries in quantum information. “I was very interested in working [with them] on what happens when there is noise in communication for interactive protocols where the usual error correction techniques don’t apply.” Error correction is an essential element towards reducing the environmental disturbances often referred to as noise that can influence the stability of a quantum state in a quantum computer system.

These questions are also relevant to quantum cryptography and online communications security. “Factorization is a classic problem – the difficulty of factorization as at the heart of the most widely used protocols for securing communication over the Internet. If we had a quantum internet, we could use it to do key distribution and so, have communications that are perfectly secure” says Prof. Touchette.

It was under the supervision of quantum optics theorist Norbert Lütkenhaus that Dave Touchette became interested in quantum key distribution and what was being achieved in the laboratory. “We tried to push to see how the tools I had developed could be applied in the framework he was interested in. It created a new focus in this area.” Together, they developed protocols using elements from quantum optics that allow distributed computing across multiple nodes while revealing less information than the best classical protocols.

Contributing to the next generation in Quebec

When he finished his postdoctorate, he knew he wanted to stay in North America and return to Québec. “I was drawn by the excellency and dynamic nature of the research at IQ. Now that I’m here, I’d like to collaborate on questions in quantum computing and how we can translate the hardware aspect to architectures that are being developed here at IQ.”

He does not shy away from his motivations to contribute to the next generation of researchers in his field. With the growing needs of an emerging quantum economy, Prof. Touchette believes it is important to attract new talent, particularly at the bachelors level, to take a greater interest in quantum computing: “There will be a need for people trained in quantum without being at the cutting edge of research. We want and must continue to train excellent future researchers in the field, but also train a workforce that can meet the needs of the industry and be able to enter the market quickly. It’s very exciting to be in the middle of all this as it unfolds.”

It is safe to assume that Prof. Touchette’s passion and expertise will continue to push the limits and contribute to the development of his rapidly expanding field.


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