Former director of the Service de Physique Théorique de Saclay (1979-1987) [1], our friend and colleague Roger Balian has just published with his collaborators Armen Allahverdyan, Yerevan Physics Institute, and Theo M. Nieuwenhuizen, Institute for Theoretical Physics Amsterdam, on the journal Comptes Rendus. Physique de l'Académie des Sciences [2].

In this publication, the authors present a graduate course on ideal measurements, which are dynamic processes coupling the quantum system under test and a measuring device, analyzed within the framework of quantum statistical mechanics: this analysis helps clarifying the meaning of Born's rule and von Neumann's reduction.

[1] Short biography in « Roger Balian is 80! »

[2] Comptes Rendus. Physique 2024, Vol. 25, p. 251-287. https://doi.org/10.5802/crphys.180