Quantum Phase of Free Fall Measured for First Time — SkimNews
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- An international team including Nobel laureate Sir Roger Penrose directly observed a long-predicted gravitational effect in a falling quantum object, publishing results September 2 in Science Advances.
- Researchers built the Quantum Galileo Interferometer, which split an atom's quantum wave into two paths—one held stationary while the other fell freely—then reunited them to measure the accumulated phase difference.
- The experiment used clouds of rubidium atoms cooled just above absolute zero and manipulated near a specially designed atom chip at Ben-Gurion University of the Negev.
- The measured quantum phase matched the prediction that follows when Einstein's equivalence principle is extended to quantum objects, showing the principle remains compatible with quantum mechanics within the tested range.
- Lead author Ron Folman said the work combines a hard experiment with far-reaching theoretical interpretation about unifying gravity and quantum theory—the two frameworks that have resisted all attempts at a unified description.
- The researchers plan to extend the technique to heavier objects like nanodiamonds, which could eventually test Penrose's hypothesis that quantum mechanics breaks down for sufficiently massive objects held in superposition long enough.
Why it matters: The experiment provides the first direct laboratory confirmation that Einstein's equivalence principle survives when extended to quantum objects, tightening the constraints on theories that try to unify general relativity and quantum mechanics. The team's planned scale-up to nanodiamonds could eventually put Penrose's controversial collapse hypothesis to an empirical test rather than leaving it as pure theory.
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