Physicists observed a quantum state change in ultracold atoms. This change matched Einstein's equivalence principle for a freely falling object. The experiment used a Quantum Galileo Interferometer with rubidium atoms. Researchers measured quantum interference after separating and recombining atomic waves. This finding confirms Einstein's gravity theory holds for quantum matter.

Physicists have directly observed a long-predicted quantum effect of gravity, putting one of Einstein’s foundational ideas to a striking new test. Using ultracold atoms,…

An international team of researchers directly measured gravity’s predicted effect on the quantum phase of freely falling atoms.