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Studenten im Sommer auf dem Campus Nord, rote Zahnräder im Hintergrund © Roland Baege​/​TU Dortmund
QUANTUM STORAGE

Three Questions for Humboldt Fellow Dr. Arnault Raymond

© David Nils Müller​​​/​​​TU Dortmund University
Dr. Arnault Raymond is a physicist and Humboldt Research Fellow at TU Dortmund University, where he conducts research on photon echoes in semiconductor nanostructures.
Since the start of the winter semester, Dr. Arnault Raymond has been a visiting scholar at the department of Physics at TU Dortmund University. For two years, the Humboldt Research Fellow from the Université Paris-Saclay will be conducting research here on photon echoes in semiconductor nanostructures—and exploring how these can be used to build quantum memory. In this interview, he discusses his current project, potential future applications, and the value of international collaboration.

Mr. Raymond, what are you currently researching?

Here at TU Dortmund University, I’m studying photon echoes in semiconductor nanostructures—and, above all, how this phenomenon can be harnessed for quantum information technologies. You can think of it something like this: A material “remembers” the information carried by a light pulse and emits it as light as soon as a second light pulse triggers it to do so. That’s exactly what makes photon echoes so exciting for quantum technologies: they could be used to store optical quantum information in a solid-state device and retrieve it when needed. That would form the basis for what’s known as a quantum memory. At the same time, photon echoes are an excellent tool for studying charge carriers and spins in semiconductors: What quantum properties do they have, and how do they interact with light and with each other?

In my project, I’m taking a close look at photon echoes in a wide variety of semiconductor systems—from quantum wells to quantum dots to perovskite nanocrystals. On the one hand, I want to store and retrieve optical signals more efficiently. To do this, we embed these quantum emitters in custom-designed optical resonators. On the other hand, we aim to develop sophisticated optical measurement methods that will allow us to fully characterize the quantum properties of the emitted photon echoes. Both are important milestones on the path to quantum memory based on photon echoes.

To what extent does TU Dortmund University provide a good environment for your research?

From a technical perspective, the research group led by Prof. Manfred Bayer and Prof. Marc Aßmann has outstanding expertise in spectroscopy of semiconductor quantum emitters. They have done truly pioneering work on photon echoes in semiconductor systems, and just recently they developed an optical homodyne detection method—exactly what’s needed to characterize the quantum states of photon echoes. With their combination of expertise in ultrashort-time spectroscopy, quantum optics, and semiconductor systems, coupled with a strong theoretical foundation in spin physics and light-matter interactions, the environment for such an ambitious project could hardly be better.

Furthermore, basic research and technical applications go hand in hand at TU Dortmund University. Within the local research and innovation landscape, one can explore how fundamental knowledge eventually gives rise to new technologies. This is particularly relevant for a project that could one day lead to quantum information technology. And last but not least, I can continue to develop both professionally and scientifically here, for example within the Ruhr University Alliance. Through these networks, I can forge new collaborations and, hopefully, continue to develop some of our shared ideas even after my research stay has ended.

What are your plans for your time in Dortmund—and what makes this international collaboration special?

I’d like to delve even deeper into semiconductor optics here, learn new spectroscopic techniques, and explore new research approaches at the intersection of fundamental physics, photonics, and quantum information. This collaboration is particularly valuable because it brings together my expertise in quantum optics and photonic devices with the experience in ultrashort-time spectroscopy and semiconductor physics at TU Dortmund University. By combining these perspectives, we can examine research questions from a wide variety of angles and develop new ideas. 

And beyond the current project, I hope that this will lead to a lasting scientific bridge between Germany and France, facilitating new joint projects, the exchange of knowledge, and research stays for students and early-career researchers.

About Dr. Arnault Raymond

Dr. Arnault Raymond earned his Ph.D. in 2023 from Université Paris Cité. The topic of his dissertation was spatially entangled light in photonic semiconductor circuits. He then conducted postdoctoral research in France on quantum dots and semiconductor nanostructures before joining TU Dortmund University in October 2026 as a Humboldt Research Fellow.

About the Humboldt Research Fellowship

Through its research fellowship, the Alexander von Humboldt Foundation enables exceptionally qualified, experienced researchers from abroad to carry out their own research projects in collaboration with hosts at a research institution in Germany. The program is aimed at postdocs and experienced researchers who have completed their doctoral degrees within the last twelve years.

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