Susana F. Huelga

Two spinning tops whirl in an invisible dance, tied together by a thread of spacetime. One of them, massive and rotating, is in a superposition of two opposite directions of rotation. The second, a light test particle, moves in a circle around the first. Their motions intertwine, generating quantum entanglement through the gravitational field.

A drop of ink in a glass of water spreads in intricate swirls. Similarly, a quantum particle exchanging energy with its environment changes its state in a complex and entangled manner. Describing this dance between particle and environment has long baffled scientists.