Christian Bordé is the inventor of saturated absorption spectroscopy, which is now an essential component of many scientific experiments and instruments, particularly in molecular spectroscopy and in the field of cold atoms. His research in this field has enabled him to demonstrate many new effects in molecular and atomic physics. One of the most notable was the resolution of the recoil doublet in saturated absorption spectroscopy, the first quantitative demonstration of the conservation of momentum between an atomic system and light.
His work in atomic spectroscopy subsequently led him to design a spatial atom interferometer based on the recoil effect of the atom-photon interaction. The Ramsey-Bordé interferometer is now the central element of many fundamental physics experiments, as well as high-precision quantum sensors.
He has also developed a new relativistic atomic optics based on the quantum treatment of atoms’ proper time, which has led him to generalise Fermat’s principle to five-dimensional space.
Christian J. Bordé has developed close links with SYRTE throughout his career. Towards the end of the 1990s, he supported the start-up of experimental activities in atomic interferometry, first at the LHA, then at SYRTE, following the merger of the LPTF and LHA laboratories, in which he played a very active role. In particular, he was involved in the development of the cold atom gyrometer, the first instrument of its kind in the world, and in large-scale projects such as the HYPER space project, which made a major contribution to structuring the community on a European scale.
Since 2004, he has been assigned to SYRTE, where he worked part of the time until his retirement in 2008, and then as an emeritus. There he continued his theoretical work on the modelling of inertial sensors, a difficult subject that he has continued to develop in recent years. He attached great importance to disseminating the results of his theoretical work and his vision of physics, particularly to young researchers, with whom he was always ready to exchange ideas.0
To mark his 80th birthday, we organised a half-day scientific symposium at the Paris Observatory on 31 May 2023, in conjunction with the Laboratoire de Physique des Lasers, to pay tribute to his scientific career. The event brought together specialists from different fields of research and provided an opportunity to measure the strong impact that Christian Bordé’s work and personality have had on today’s experimental physics and the people who do it, both in France and abroad.
Appointed Chevalier de la Légion d’Honneur in 2011, Christian J. Bordé was a member of the Académie Française, a founding member of the Académie des Technologies, a member of the European Academy of Sciences, a member of the Metrology Committee and Co-Chairman of the Science and Metrology Committee of the Académie des Sciences.