Physicists confirm Einstein gravity effect in quantum realm

An international team of researchers led by Ben-Gurion University of the Negev, the University of Ulm, and the University of Oxford observed the effect of gravity on a falling quantum object on September 2, 2026. The experimental finding confirms that the core equivalence principle established by Albert Einstein remains fully valid when applied to matter at the subatomic scale.

The particles fell freely.

Scientists conducted the physical trials at Ben-Gurion University by manipulating clouds of rubidium atoms cooled to temperatures just above absolute zero near the surface of a custom-built atom chip. Professor Sir Roger Penrose joined the investigation alongside lead author Professor Ron Folman and doctoral researcher Or Dobkowski to record the quantum phase shift directly. The team documented that matter in wave states mirrors the classical behavior predicted for falling bodies.

Splitting atomic trajectories with the Quantum Galileo Interferometer

The experimental setup relied on a specialized system known as the Quantum Galileo Interferometer to divide the atomic wave into two separate paths. Using initial microwave pulses, the physicists placed the ultracold rubidium atoms into a quantum superposition where each particle traveled along dual trajectories simultaneously. Tiny electrical wires embedded inside the atom chip generated controlled magnetic fields to direct the separate routes.

One path counteracted gravitational pull entirely.

While an upward magnetic force held that first atomic section stationary relative to the laboratory and Earth, a magnetic pulse propelled the second section upward into a ballistic trajectory. The researchers then modified the magnetic sensitivity of that second path, allowing the rubidium cloud to drop under gravity in a motion identical to a thrown mechanical ball. This controlled descent enabled an isolated comparison between motionless and falling atomic components.

A final magnetic pulse reunited the two separate waves at the conclusion of the free fall. The deliberate collision generated an interference pattern that let the scientists calculate the accumulated difference in quantum phase between the stationary atom cloud and the dropped cloud.

Direct measurements align with the equivalence principle

The recorded phase difference matched the exact mathematical value derived when applying the gravitational equivalence principle of Albert Einstein to quantum wave functions.

The equivalence principle states that gravity disappears locally for an observer in free fall, a phenomenon traditionally illustrated by an elevator plunging without resistance. While classic experiments confirmed this behavior for macroscopic matter across decades of field testing, physical measurements of wave-like quantum entities had never isolated this specific phase shift until now. The outcome creates a documented physical connection between the mechanics of general relativity and quantum theory.

Professor Ron Folman addressed the scope of the empirical observation following data analysis.

“This is a unique paper, in the sense that it combines a hard experiment with a far-reaching theoretical interpretation about one of the most fundamental questions in physics: How can gravity (described by Einstein’s theory of relativity) and quantum theory be unified into one understanding of the universe? These two pillars of modern physics have so far eluded all attempts at a unified theoretical framework, but this complex experiment gives more hints as to how such a unification may be achieved,” said Folman.

Testing quantum mechanical limits with heavier masses

The findings demonstrate that the equivalence principle functions within the analyzed parameters without proving that gravity itself possesses quantized properties. Professor Vlatko Vedral from the Department of Physics at the University of Oxford explained that quantum mechanics continues to operate without theoretical breakdown in this gravitational zone.

“We have no consistent theory telling us why quantum physics should fail. This experiment pushes quantum mechanics into one of its most intriguing frontiers, gravity, and shows that, once again, its predictions hold,” said Vedral.

The data does not refute the theoretical proposition formulated by Professor Sir Roger Penrose regarding mass thresholds.

Penrose argued that quantum superpositions naturally decay when applied to sufficiently massive objects over extended durations of time. The present experiment did not evaluate the mass scales or time intervals required to test that specific hypothesis directly. A subsequent trial focused on heavier objects operates under the direction of the same research group at Ben-Gurion University of the Negev.

Participating laboratories and formal publication records

The research sequence brought together specialists from six academic and technological centers across several countries:

• Ben-Gurion University of the Negev
• University of Oxford
• University of Southampton
• Universität Ulm
• Institute of Quantum Technologies at the German Aerospace Center in Ulm
• Texas A&M University

The upcoming research phase at Ben-Gurion University of the Negev incorporates nanodiamonds to determine whether higher mass scales disrupt atomic superposition. Formal documentation appeared under digital object identifier 10.1126/sciadv.aec8045.