Exploring the limits of quantum mechanics with massive objects

A fundamental feature of quantum physics is the existence of superposition states. They are, e. g., created in a double slit experiment, where a particle passes through both slits of an interferometer at the same time to interfere with itself downstream. This spatially separated quantum superposition has been observed for particles ranging from electrons to complex molecules. But what happens for even more massive systems? The achievement of large superpositions of heavy objects should confront some conjectures that predict the breakdown of the quantum superposition principle at larger scales.