Two separate clouds of ultra-cold atoms can be linked together using nothing but the force of gravity to prove that gravity itself is quantum.
April 24, 2026
Original Paper
Gravity mediated entanglement of phonons in Bose-Einstein condensates
arXiv · 2604.20767
The Takeaway
Phonons in two separate Bose-Einstein condensates can be entangled using gravity as the sole mediator. This experiment would prove that gravity is a quantum force because a classical force cannot create quantum entanglement between two objects. Researchers propose using these clouds of cold atoms as witnesses to the subatomic nature of the gravitational field. If the entanglement is detected, it would settle one of the biggest debates in the history of physics. This provides a concrete alternative to the multi-billion dollar detectors currently being planned to search for quantum gravity.
From the abstract
The eigenstates of two test-masses (where each test-mass is placed inside of a harmonic trap) separated by a distance, can get entangled where gravity acts as the mediator of entanglement and it has been argued in \href{this https URL}{arXiv:2511.07348[quant-ph]} that this entanglement of masses cannot be generated without the underlying quantum nature of gravity. In this work, we consider two non-relativistic Bose-Einstein condensates (formed inside of harmonic trap potentials with identical tr