Beyond huge leaps in the exploration of extreme astrophysical systems Earth-bound experiments have continuously been refined for sensing gravity phenomena on laboratory scales i.e. in the low energy limit. A yet unexplored frontier is the regime of microscopic source masses, which provides a natural path towards exploring the quantum nature of gravity. We recently demonstrated gravitational coupling between two ≈90 mg gold spheres with a systematic accuracy of 4-11m/s² and a statistical precision of 4-12m/s² in a miniaturized torsion balance experiment. We expect further improvements of the setup to enable the isolation of gravity as a coupling force for objects well below the Planck mass in the next iteration. These top down efforts strive to ultimately culminate in a purely gravitational coupling of quantum objects.
Markus Aspelmeyer (Wien): Towards quantum source masses: gravitational coupling between millimeter-sized objects
Foto: Barbara Mair