In 1963, the Neuchâtel Observatory (NO), established in 1858 with the primary task of time determination, purchased a thallium atomic clock. The introduction of this clock, designed and built in partnership with the company Ébauches SA and the Swiss Laboratory for Horological Research (LSRH), marked a turning point in the history of the NO. Astronomy was gradually replaced by quantum physics, astronomers by time-frequency physicists, the old apparatuses were falling into disuse, and watchmaking ceased being the institution’s primary industrial partner. These transformations reflected a wider historical process, since in 1967 the Bureau International des Poids et Mesures (BIPM) changed the definition of the second, taking as its reference the oscillation of a caesium 133 atom.
The project Atomic Clocks at the Neuchâtel Observatory: Time, Quantum Technologies and Innovation (1948-2001) aims to study the shift from astronomy to quantum physics for time determination, at the example of an institution, the NO, which allows to examine the scientific and technological changes associated with the adoption of atomic clocks, and to explore the process of innovation linked to this application of quantum physics. Through the history of the NO, it will be made visible how this transition constituted a major innovation front for Switzerland in the post-war period, involving scientific institutions, cantonal and federal offices, private industry, and major state-owned companies, which all aimed to give the country a central role in the development of quantum technologies. This project involves a collaboration between historians interested in the relationship between science and industry in relation to time measurement, and time-frequency physicists concerned with the history of their discipline, at a time when the BIPM is holding major discussions on a new redefinition of the second. This cross-disciplinary approach will make it possible to tackle the complexity of the technical transformations of an observatory in the age of atomic clocks, a subject that is still very little dealt with in historiography, by exploring the complexity of the instruments on the one hand, and by studying the expectations and strategies of the actors involved in this process on the other.