First Interferometer Measures Free‑Fall Effect on Quantum Wave

Scientists have built the first interferometer that can directly test how free fall affects a quantum wave. The apparatus, led by Ron Folman of Ben‑Gurion University and collaborators in Germany, the UK and the US—including Nobel laureate Roger Penrose—creates a single atom that simultaneously follows two paths: one that falls under gravity and one that is held stationary. The two paths recombine at the same point and time, allowing the experiment to measure the phase shift induced by gravity on the atom’s wave function. The experiment confirms the long‑awaited prediction that quantum mechanics and Einstein’s theory of gravity can coexist without contradiction. The result opens a new window for precision tests of fundamental physics and could guide future efforts to unify quantum theory with general relativity.