9 September 2020 Hugues Vincelette
Graduate portrait - Karl Thibault

Contribute to the growth of IQ

Karl Thibault and Bertrand Reulet

Photo : IQ

On April 1, 2019, Karl Thibault began his job at the IQ as Coordinator – Entrepreneurship and Scientific Program. He had not yet defended his doctoral thesis. He reconciled this new job with the end of his doctoral thesis writing, which he completed seven months later.

Synchronizing more than one thing at a time is an integral part of Karl’s daily life, as he organizes Horizon activities, participates in entrepreneurship development, and contributes to the development of the IQ science program.


At the end of his college studies at the Cégep de Sherbrooke, he hesitated between mathematics and physics, “the two subjects that were both a challenge and in which I had an interest”. He chose physics and began his career at the Université de Sherbrooke, which took him from an undergraduate degree to a doctorate. “After spending more than ten hours on our first mechanics assignment, I realized that I was no longer in CEGEP and that my years at la Frontalière high school were far behind me!” confides Karl.


His involvement in student projects took place very gradually. “I had little experience in participating in extracurricular activities before my master’s degree. It boils down to coaching a high school basketball team while I was in CEGEP. When I arrived at the master’s level, the Jeux de la physique existed but had never been organized in Sherbrooke. My friends and I decided to organize it and I had the opportunity to chair the organizing committee. It was my first real experience in event planning and a huge learning experience for me, both personally and professionally. My friends and I can attest that the adventure was not always easy, but I remain satisfied with the end result. This is where I found out that I really enjoy being involved in organizing events. I then participated in the organization of various conferences during my graduate studies, as well as in the structuring of Q2 toward the end of my doctorate,” explains Karl Thibault, who was also a member of the Ultimate Frisbee Sports Club of the Vert et Or of the Université de Sherbrooke.

Professor Bertrand Reulet’s Group

Karl’s undergraduate studies were done in a cooperative regime. He did successive internships in Professor Sénéchal’s group in theoretical physics, another at the Canadian Light Source in Saskatchewan in experimental physics, then another in Professor Bertrand Reulet’s laboratory.

He describes the latter: “I helped establish his laboratory and learned the basic techniques of cleanroom manufacturing. Of my three internships, this is the one I liked the most. So, I decided to do a master’s degree in his research group. I liked the ambiance of the group and manufacturing in a cleanroom. My contribution to the initial laboratory setup seemed to bind me to this team.”

Here is what Professor Reulet had to say about Karl: “Over the years spent in my group, I have seen the brilliant and curious student, Karl, take up our difficult research subjects, whose success is far from guaranteed, to make great achievements never before explored, with complex experiments and supporting theoretical development. I admired his driving role in my team and his dynamic involvement in the student community in Quebec for the influence of physics. Our institute today benefits from his commitment and his passion, and I am very happy about it.”

The Doctoral Project

This project saw its beginnings during Karl’s master’s degree. After about a year, his master’s degree shifted toward another topic: the effect of the Pauli and Heisenberg Principles on quantum electronics transport and current fluctuations. However, this shift was only a postponement for the initial project, which will resurface at the doctoral level. “I started to try to understand the interplay between two coupled tunnel junctions. As we moved forward with the project, my director and I determined that it was difficult to achieve in two years.”

“At the doctoral level, we wondered if there are other ways to visualize this interaction and to develop models that deal with the feedback effect of noise. We have studied in detail the influence of the environment on tunnel junctions integrated to an electrical circuit, a mechanism known as the dynamical Coulomb blockade effect. It’s usually explained by theories which are generally based in microscopic phenomena of transport within the tunnel junction. In our opinion, it is possible to find an explanation based on fluctuations. The model we developed led us to believe that this phenomenon could occur in a component other than a tunnel junction. To see this effect, the noise has to depend on the voltage, that is, the current fluctuations in the device depend on the voltage across it,” describes Karl.

Researchers thus set out to find devices whose noise depended on current. They identified avalanche diodes: “I did manipulations on the avalanche diodes. We noticed that there were effects caused by noise feedback in the avalanche diodes which changed its intrinsic properties when placed in a resistive electromagnetic environment. This result goes against classical circuit theory that says an electrical component has certain intrinsic properties that do not change, regardless of its environment. However, this is not what happens experimentally with the diode in certain regimes where the noise depends on the current,” explains Karl.

In His Position at the IQ

In the spring of 2019, the IQ posted a position for the coordination of entrepreneurship and the scientific program to broaden its scope. After the hiring process, Karl got the position. “I fully support the IQ’s vision, including that of putting students at the centre of the research. The opportunities that gave me the experience I needed for this role, like my involvement in Q2, were partly given to me by the IQ. I therefore want to continue to provide such favourable conditions for the IQ’s student community, ensuring that scientific activity continues its momentum, that there is a diversity of representation within seminars, try to ensure that the IQ offers its student community good conditions, a culture, and a work atmosphere that promote the development of its scientists are some of my objectives. The development of the ecosystem that continues to grow around the IQ is a remarkable source of motivation and I am happy to contribute to it,” concludes Karl.

Who better than someone who knew the IQ as a student to be its ambassador? Congratulations on your doctorate, Karl, and have a good experience with the IQ team

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