Graduate portrait

Patrick Bourgeois-Hope obtains his PhD

Photo : Institut quantique

Patrick Bourgeois-Hope concludes his academic career at the Université de Sherbrooke, where he completed his MSc and PhD in the group of Professor Louis Taillefer. 

His background 

As early as high school, Patrick had a great interest in physics and already knew that he wanted to work in this field later on. 

Born and raised in Granby, he completed his college studies in Pure and Applied Sciences at the Cégep de Granby, and then went on to complete a bachelor’s degree in Physics and Mathematics at McGill University in Montreal. 

After his bachelor’s degree, Patrick wanted to continue on to the master’s level, but did not have a clear idea of the subject on which he wanted to work. However, he was particularly interested in quantum materials and quantum computing. When he discovered that the physics department at the Université de Sherbrooke specialised in these two areas of physics, he thought it would be a “perfect match”.  

After two visits to UdeS, during which Patrick was able to feel the warm atmosphere of the city and meet Prof. Louis Taillefer’s research group, he concluded that Sherbrooke would be an ideal environment for his graduate studies. 

His research projects 

Patrick’s master’s and doctoral research projects, carried out in Prof. Louis Taillefer’s group, focused on thermal transport measurements on various quantum materials. 

For his thesis, Patrick focused on thermal conductivity measurements on cuprates and strontium ruthenate, two types of superconductors, as well as on magnetic materials called quantum spin liquids. 

“Cuprates have a very complex phase diagram. There are several phases, and it is not clear whether they compete or how they are related to each other, so we wanted to study the relationship between the different phases. In this project, I showed that there is a magnetic order that negatively affects thermal transport, which allows us to better understand the effect of the magnetic order in this phase diagram,” says Patrick. 

His results have also caused the scientific community to reconsider some paradigms. 

“Previously, there was widespread notion in the field that strontium ruthenate had a particular symmetry that would make it a very exotic superconductor. This symmetry would cause it to have excitations which would potentially make it usable for quantum computing. There was a big buzz around this material, everyone wanted to believe this was indeed reality. Our results were among the first that went against this theory. Now the paradigm has shifted, and no one thinks this exotic state is still likely. “ 

As for quantum spin liquids, Patrick’s results showed that they do not possess mobile spin excitations, in contrast to what an earlier study had stated.  

“A quantum spin liquid is a somewhat exotic magnetic state, in which the theory predicts that there should be mobile spin excitations that we call a spinon. What we have shown is that there is no evidence of these mobile spin excitations. Since thermal conductivity allows us to see the mobile particles that contribute to thermal transport, we could have seen evidence of heat transport generated by these excitations, but there was none. “ 

According to Patrick, contradicting results is not necessarily the most glamorous job for a researcher, but it is an essential task: “When you contradict a popular result, it’s a bit thankless and people have more difficulty accepting your version of the facts, but it’s still a necessary job to check whether or not the results obtained by other researchers are reproducible. “ 

His thesis supervisor, Prof. Louis Taillefer, is impressed by the impact of Patrick’s work: “During his PhD, Patrick mastered a cutting-edge experimental technique, thermal conductivity, at temperatures very close to absolute zero. He was able to use this tool to elucidate three of the hottest topics in the field of quantum materials. Quite a feat! “ 

His academic involvement 

During his graduate studies, Patrick took part in the organisation of activities within the Diversity in Physics Committee of the Université de Sherbrooke (DiPhUS) and the Q2 – Student Entrepreneurship. For him, these committees are necessary and bring a lot to the university community. “I learned a lot through my involvement in DiPhUS. There’s a real need for it and it’s a cause that I really care about. “ 

As for Q2, a new branch of the Institut quantique that helps students steer themselves towards the job market, Patrick explains that his involvement has opened his mind to the many possibilities for a career in physics. “When you’re doing fundamental research, you’re a little disconnected from the entrepreneurial side of things because it’s harder to envision founding a start-up rooted in your field of expertise. When I first got involved in Q2, the committee’s vision was a little fuzzy to me, but then I adopted the entrepreneurial mindset. I have no intention of going into business, but I have a better appreciation of what it entails. You start being more aware of the many different possibilities when you’re around entrepreneurs, people who are passionate, people who work in other fields, and that’s what my involvement in Q2 has allowed me to do, to get inspiration. ”  

What’s Next 

For the future, Patrick wants to move towards new challenges in industry, where he hopes to find a job in microelectronics. He would like to stay in the Eastern Townships, but he will see where life takes him. Good luck Patrick! 

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