Frédéric Magniez, at the Crossroads of Mathematics and Computer Science

BACKGROUND  

Former student at the Department of Mathematics at ENS Paris-Saclay (formerly ENS Cachan), Frédéric Magniez is an agrégé in mathematics and a doctor in computer science. He joined CNRS in 2000 at the Laboratory of Research in Computer Science (LRI) and was accredited in 2008. In 2013, he joined the Institute of Fundamental Computer Science Research (IRIF), where he leads the Algorithms and Complexities team. Additionally, he was a researcher and associate professor at Polytechnique from 2003 to 2015. In 2015, he became the deputy director of the Fondation Sciences Mathématiques de Paris, then took over the direction of IRIF in 2018. He holds the chair in Computer Science and Numerical Sciences at the Collège de France for 2020-2021.

RESEARCH

Frédéric Magniez works on the design and analysis of probabilistic algorithms for processing large datasets, as well as the development of quantum computing, focusing on algorithms, cryptography, and its interactions with physics.

What are your activities as a researcher/director of IRIF/professor at Collège de France?

I am primarily a researcher at CNRS, specifically a Research Director. My research revolves around designing new algorithms, whether for our current machines facing new challenges or for future machines like quantum computers.

The role of a researcher involves various activities. 

One of them is research management. In this capacity, I lead the Institute of Fundamental Computer Science Research, a flagship in French research dedicated to everything upstream of our everyday computing. It involves theoretical innovation that may later lead to technological innovation. 

Another activity is, of course, knowledge dissemination. This year, I am teaching at the Collège de France as part of an annual chair, unfortunately only for a year. This chair was entrusted to me to teach quantum algorithms, a new way of thinking about computing on an emerging technology."
 

What are your favorite topics as a mathematician and computer scientist?

 I love identifying and understanding what we call algorithmic bottlenecks. It's about understanding what is difficult for a computer in a complex problem. Often it's just a simple and seemingly trivial task. For example, how to count the number of distinct words in Zola's work with only 10 fingers? 

Then I tackle it and try to make it easier, perhaps by changing it a bit, i.e., with different rules of the game. This is what we do with quantum algorithms. We changed the machine! I am also interested in probabilistic algorithms that compute faster by randomly generating numbers when faced with too many possibilities to explore, as is done now in artificial intelligence. 

This research is situated between computer science and mathematics. While the motivations are clearly computational, the tools developed and the approach are mathematical

What led you to quantum computing and algorithms?

The breakthrough happened in two stages. The first was when my internship supervisor at ENS Paris-Saclay (formerly ENS Cachan), Alain Finkel from the Computer Science department, proposed a thesis on an article dealing with quantum cryptography. He introduced me to the right people who spoke passionately about their research. I was surprised at how doors seemed to open so easily at that time. In hindsight, I understand better. As a researcher and sometimes a teacher, I am always flattered when a student shows interest in my work and teachings. 

At that time, I was torn between computer science and mathematics. Alain Finkel's classes initially convinced me that I enjoyed computer science because it combined what I liked about mathematics with my passion for programming. 

Regarding the quantum theme, it was more complicated. I indeed met my future thesis advisor, Miklos Santha, in a second stage while attending one of his courses. The beauty of the concepts of probabilistic and quantum algorithms he taught fascinated me. But I also wanted to continue with Alain Finkel. These two professors guided me and allowed me to "try" both paths. 

In the end, quantum computing convinced me.

You have a rich and diversified background; what experience are you most proud of?

I am not the type to be proud. I believe that the recognition and trust I have gained from my community and colleagues in leading my laboratory, or in the chair I hold at the Collège de France, as well as other animation and responsibility actions I have taken, are the most beautiful recognitions of which I am, in a certain sense, very proud.

During your inaugural lecture at the Collège de France, you mentioned your time at ENS Paris-Saclay; what are your memories of that period?

I did not know the institution well before entering. I discovered classmates who were more like me than I would have imagined. We formed a very close-knit group in which I developed. 

I remember the back and forth on the RER from Cachan to Orsay because at the time the campus was in Cachan, and the course program was in Orsay. Ironically, the two seem to have finally found each other today. I also remember the classes we took together and reviewed as a group. I also remember the evenings on campus where some debated politics and others freshly learned mathematical theories. We also exchanged our khôlles, of which we were very proud to give in our former preparatory classes. I also remember the ease of being able to follow the training of my choice. I was able to enroll in two licenses because at the time there was no mathematical-computer science license.

And what would be your best memory?

Of course, the Kfet with the Kokarde, but also my experience in the BDE candidacy

What did your education provide you that has been very useful in your career?

I was able to acquire a broad knowledge of computer science through the courses I had at ENS Paris-Saclay, as well as mathematics. Preparing for the mathematics agrégation, and obtaining it, allowed me to strengthen my knowledge in mathematics, which has been very useful to me later on. The agrégation also provided me with security in my thesis by eliminating the anxiety of getting a position. What a luxury! I even had the luxury of hesitating between 2 theses and choosing the one for which I should not have had funding but eventually obtained it.

And now, what are your projects?

I have always wanted to keep a significant part of research in my activities while balancing it with other actions. I wish to invest even more in this extraordinary adventure that is emerging around quantum technologies, especially the possible construction of a fully quantum computer. I will therefore work closely with the machines that are being built to find concrete applications based on the algorithms I have developed so far. I also want to get involved in another collective task useful to the greatest number after the direction of IRIF.