Edith Grosbellet
Edith Grossbellet: Can you present yourself in a few words?
Nicolas Bachelard: I have been trained in physics as an undergraduate student in France at the Ecole Normale Supérieure de Cachan (ENS Paris-Saclay) After a specialization in optics in an engineering school called Sup Optique (Institut d'Optique), I decided to realize a PhD at the Institut Langevin in Paris. I carried on research with two post-doctoral positions. The first one was at the University of California Berkeley between 2015 and 2018. I am just starting the second one at the Technical University of Vienna in Austria.
E.G: Could you explain us briefly your projects?
N.B: Since my PhD, I have been interested in “controlling the disorder”. Indeed, at nano- or micrometric scales, structures have imperfections, which are inevitable in any fabrication processes. Even if they seem negligible, these imperfections somewhat accumulate, which deeply affects the performances of photonic devices. For instance, if you take a waveguide—i.e. an elongated geometry supposed to guide the light from A to B—the presence of small imperfections sometimes annihilates the transmission of light through it. In other words, you cannot use the information contained in the luminous signal anymore. My projects aim to develop methods such as the light exiting a disordered system can be organized. Basically, I try to restore a certain order in a system where there is none.
copyright _ © CNRS Photothèque-CyrilFRESILLON
E.G: What did motivate you to go to the US for your first post-doc?
N.B: First, it is nowadays highly recommended for young researchers to work in a foreign country. The question about an international post-doc experience is asked when you apply at CNRS for a research permanent position in France. Therefore, I thought that staying in France before applying to CNRS would be detrimental for my career. Secondly, the dominant factor in my decision was that my boss, Professor Xiang Zhang, offered me to choose my own subject. Finally, I have to admit that I was attracted by the worldwide reputation of a university such as UC Berkeley. I knew that their labs have a lot of resources, gather a lot of very good students and researchers. Overall, it represented a very dynamic environment to do research, meaning an amazing opportunity for me.
E.G: Can you compare your post-doc in the US with your previous experience in France?
N.B: The two experiences were very different but both rewarding. At UC Berkeley, I was lucky to be given carte blanche for my subjects. My boss, Professor Xiang Zhang, is an influent physicist having substantial funding. He really encourages boldness and risk taking in his students’ projects and is ready to support you financially if he believes your ideas can be successful. In France, as a freshman year PhD student, I was definitively not ready to propose a research topic. Since I had a lot to learn, I stayed in line with my PhD advisor’s topic of research. Yet, my advisor was very accessible. I was able to exchange and spend a lot of time with him, which is a relation harder to get in a bigger group.
E.G: Would you say that “risk taking” is a characteristic of the US scientific research?
N.B: My advisor at UC Berkeley likes to take scientific risks but I do not know if he is representative of the norm amongst US universities. Yet, my feeling is that in the very prestigious ones, such as Harvard or Stanford, professors have to be risk-takers. The pressure to get grants and high impact papers in order to secure your tenure is important. In the US, researchers are usually first offered a tenure track. It is a process by which an assistant professor can become a full professor after evaluation. It can be a long process before people get their tenure, i.e. a secured professor position. I was told that in prestigious universities the rate of success can lower down to roughly a third. In my mind it means that you have to publish in high impact factor papers, meaning that the risk taking component is inevitable.
E.G: How would you qualify your experience at UC Berkeley in overall?
N.B: It was a very positive one. The important diversity of projects, methods and skills in the lab considerably increased my scientific culture. During my PhD, I worked on one type of experiment, while during the same time in my post-doc, I worked with three times as many experimental platforms. It was a very dynamic environment, stimulated by many interactions between students and post-docs of different backgrounds. The downside was an important pressure to publish, especially because I am at the point of my career where I need high impact papers if I want a permanent position. People in the lab published mostly in high impact factor journals, such as Nature journals, which really puts you under a lot of pressure.
E.G: Did you encounter difficulties to come back to Europe?
N.B: I applied last year for the CNRS and will try it again next year. It is pretty hard to apply in France when you are so far away. Since I applied to different CNRS sections, I had to stay one month in France, which was hardly compatible with my work schedule in Berkeley—not to mention the price of the plane tickets. I am now starting a new post-doc in Vienna. Being in Europe is easier to develop your network by accessing more European conferences and meeting local researchers. Some grants, such as the Marie Sklodowska-Curie fellowship, help post-docs to come back to Europe after staying in the US. But with many applicants, the competition is fierce to get them! It is only the start for me, so we will see how this new adventure in Europe carries on. My goal would be a permanent position in France or its European neighbors.
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