A single qubit entangled with a beam of light through gravity could finally prove that the graviton actually exists.
April 29, 2026
Original Paper
Witnessing entanglement between photon and matter due to graviton exchange
arXiv · 2604.24496
The Takeaway
Gravity remains the only fundamental force that has never been observed at the quantum level. This experiment uses a specific setup to see if a tiny bit of matter and a photon can talk to each other using nothing but gravitational exchange. If they become entangled, it means gravity must be quantized just like electricity and magnetism. Physicists have spent decades trying to reconcile Einstein smooth space-time with the jumpy world of atoms. Finding this connection would settle one of the biggest debates in science. It would confirm that gravity is a quantum force like everything else.
From the abstract
The paper presents a scheme to detect entanglement arising from the quantum nature of gravity between a spin qubit and photons, using Stokes parameters. One of the crucial tests of the general theory of relativity is the bending of light due to the curvature. Recently, a quantum counterpart of this experiment to test the quantum nature of the gravitational interaction has been proposed, in which the spin-2, massless graviton yields entanglement between matter and a photon sector. Hence, it provi