Our Department is once again confirmed as a leader in Europe in the field of quantum mechanics with the publication in Nature Physics of an article on the future of non-interferometric tests of collapse models. The research team, led by Prof. Bassi, is composed of researchers from Queen's University Belfast, University of Southampton and the National Institute of Nuclear Physics (INFN), as well as our University.

In the article "Present status and future challenges of non-interferometric tests of collapse models", the researchers describe the present status of the experimental bounds on collapse models, which range from single atoms up to cosmology.

Quantum mechanics revolutionized our understanding of Nature. Its superposition principle describes the possibility of a system being prepared in two distinguishable physical configurations, for example, two distinct positions, and its application has already led to the development of several quantum technologies. Although countless experiments have verified the validity of the quantum theory at the level of single atoms and molecules, its universality up to the macroscopic scale is challenged on the daily basis. At the human scale, we do not perceive quantum superposition, meaning that – somewhere between the microscopic scale of single atoms and ours – the quantum superposition progressively breaks down. Collapse models describe precisely such an effect, and their testing is pivotal in understanding the limits of the quantum theory.

The last 20 years have seen a growing interest in applications of quantum theory to different physical systems, ranging from cold atoms to mesoscopic mirrors, from phonon dynamics in crystals to macroscopic resonators. Together with the development of the finest preparation and detection techniques, a plethora of different experimental tests of the validity of quantum mechanics – and that of collapse models – has emerged.

In the article, the scientists also discuss the technical challenges of state-of-art testing and draw the path for future avenues of dedicated experiments.

This article represents a great step forward in the study of collapse models: the result of a long and fruitful collaboration between researchers from different countries, both theoreticians and experimentalists.