This talk is based on our recent experimental works on quantum controlling the center of mass degree of freedom of levitated solid-state systems - and the question whether these experiments could be extended to a regime in which one can probe the gravitational field generated by a delocalised quantum object. If possible, such "quantum Cavendish" experiments would not be described by our current theory of gravity. I will also use the time to show you what else we have been working on in Vienna during the last 24 months.

Markus Aspelmeyer is Professor of Physics at the University of Vienna and Scientific Director of the Institute for Quantum Optics and Quantum Information (IQOQI) Vienna of the Austrian Academy of Sciences.