Two tiny mirrors in a vacuum are like figure skaters in a pairs routine. Their oscillations are synchronized by an invisible gravitational thread. When cooled to millionths of a degree above zero, this thread turns them into a single quantum link — the motion of one instantly echoes in the other.
A laser writes a quantum state onto the left mirror. Thanks to gravity, the information partially transfers to the right one. Specially purified light (photons without noise) amplifies the effect.
If the experiment succeeds, it will prove the quantum nature of gravity. Two massive bodies, entangled only by gravity, will show: spacetime is quantized, similar to electromagnetic waves. Einstein sought a unified theory, and this experiment transforms it from a dream into a practical goal.
At room temperature, thermal jolts are billions of times stronger than the gravitational attraction between the mirrors. But in the cold, below a millionth of a degree from absolute zero, gravity becomes the principal conductor of the quantum dance.
The idea of gravitational quantum linking echoes the 'graviton transmitters' from science fiction — devices that use spacetime curvature for communication. Here, it's not fiction, but a lab plan.