Testing sub-gravitational forces on atoms from a miniature, in-vacuum source mass

Understand

Gravity is the weakest fundamental interaction and the only one that has not been measured at the particle level.

• Traditional experimental methods, from astronomical observations to torsion balances, use macroscopic masses to both source and probe gravitational fields.
• Matter wave interferometers have used neutrons, atoms and molecular clusters as microscopic test particles, but initially probed the field sourced by the entire earth.
• Later, the gravitational field arising from hundreds of kilograms of artificial source masses was measured with atom interferometry.