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. Atomic time is also political time and makes it possible to observe the reconfiguration of the NO role in line with the new official functions assigned to the institution in the second half of the twentieth century. To understand the history of the NO, this study identifies three phases, from 1948, the date of the first experiments with quantum technologies, to 2001, the date of the retirement of the last director who played a major role in the development of atomic clocks. The first phase (1948-1967) concerns the introduction of atomic technology, which will be studied through an analysis of the reorganization of the NO, strongly supported by political and industrial circles. The second phase (1967-1988) focuses on the NO commercial activities, which played a role in the dissemination of quantum technologies in Switzerland. The third phase (1988-2001) saw a restructuring of the relationship between science and industry in the context of innovation policy, prompting the NO to shift its focus to applied research.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. This project not only aims to explore the importance of the penetration of quantum technologies into the Swiss scientific and industrial landscape but is also a contribution to the history of innovation processes in this country in the second half of the twentieth century. For this study, the cantonal and federal archives and the archives of relevant companies will be examined, as well as the archives of laboratories and international agencies that cooperated with the NO. This work will be coupled with a study of the collections of NO instruments held in the museums of Neuchâtel, and with a campaign of interviews with scientists and industrialists who worked at the NO.