Interview with Eleni Diamanti
INTERVIEW
Interview with Eleni Diamanti
© Frédérique Plas, CNRS Images
CNRS Research Director at LIP6 Paris, the Computer Science Laboratory of Sorbonne University, and specialist of Quantum Optics, QKD and Quantum Networks, co-founder of Welinq.
https:// doi. org / 10.1051 / photon / 202513115
What first sparked your interest in science? I come from a family where discussions about science were common at home, both my parents were physicists, my mother a university professor and my father a high school teacher in physics, chemistry, and astronomy. He had a true passion for all branches of science, and we were surrounded by scientific books. Today, in turn, I try to pass on this enthusiasm for science to my children and to the students I meet.
How did you discover quantum optics? I pursued my studies in Greece. After high school, I was admitted to the National Technical University of Athens, in the Electrical and Computer Engineering department, with a demanding five-year curriculum. It was a highly engineering-oriented program with a strong scientific approach. It was during my studies in Athens that I became interested in quantum physics and its applications, including in optics, particularly through a course in this field. When I arrived at Stanford in 2000, I was in the Electrical Engineering department but I already knew I wanted to focus on this domain. I chose my PhD thesis accordingly. My PhD advisor, Professor Yoshihisa Yamamoto, had just introduced quantum cryptography to his research group and at that time, it was still an emerging topic. As my first assignment, he gave me a paper on quantum computing with photonic systems, which was far from quantum cryptography. His question was: Is quantum computing with photons feasible? After careful thought and analysis, we concluded that it was not realistic within the scope of a PhD— a conclusion that turned out to be correct, as even 25 years later, despite major
advances, photonic quantum computing still faces many challenges. So, we redirected the research topic to quantum cryptography and quantum communication, which were also still in their early stages at that time.
Did you receive any specific training in quantum optics before your PhD? Not really. I had taken a few lab courses in optics at the university, but looking back, I realize how valuable the trust placed in me was. I was assigned an experimental PhD even though I had not been formally trained in the field in depth. A senior PhD student trained me during my first few months. Comparing this to today’ s students, I notice they arrive with a much stronger background, which is clearly very helpful for the teams and also for the students. In general, nowadays, young researchers tend to be more experienced than I was at the time.
What was the topic of your PhD thesis? My PhD focused on the implementation and security analysis of a quantum cryptography protocol, which we were developing in collaboration with Japanese colleagues. I had to design a quantum cryptography system from scratch. I started with an empty optical table, gradually building up the necessary components. Another key part of my thesis was designing single-photon detectors, based on frequency conversion in nonlinear waveguides, which were fabricated by collaborators in another research group at Stanford. The outcome of my work was the development of these up-conversion single-photon detectors, along with the security analysis and the demonstration of secret key generation using a quantum cryptography system. I defended my PhD in 2006.
How did you organize your return to Europe? In 2006, I returned to Europe, thanks to a double Marie Curie MSCA fellowship. At the time, it was possible to obtain two types of grants simultaneously: a returning European fellowship, allowing a European citizen to return from abroad and work in another European country, and a second grant to finance scientific projects for postdoctoral scholars. This was a perfect fit for my situation since I was Greek and applying to a position in Philippe Grangier’ s group at the Institut d’ Optique( IOGS) in France. The first grant covered my salary, and the second funded my research project. This created ideal conditions for my return to Europe. I didn’ t even consider other opportunities in the US— it was Europe or nothing.
Can you describe your MSCA research project? The project was focused on quantum cryptography, but approached through a different type of protocol called continuous-variable quantum key distribution( CV-QKD). This protocol still relies on quantum optics but is conceptually quite different. When I arrived as a postdoc, the main challenge was making these systems deployable in real-world applications. Philippe Grangier was among the leaders in a European project aimed at developing such systems. I contributed to creating CV-QKD prototypes, with the goal of deploying and operating them in real-world settings. This experience allowed me not only to learn new concepts on continuous variables but also to get hands-on experience with practical aspects of quantum communication infrastructures. These are topics I continue working on today, in various contexts. Looking
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