Atoms Get Entangled in Space: A New Kind of Quantum Link express
Usually, quantum entanglement links internal properties, but here, for the first time, the positions of two atoms are entangled. Like a pair of dancers, one can move only if the partner freezes — but which one moves is unknown beforehand due to quantum uncertainty.
The secret lies in giant atoms: with precise laser spectroscopy, an electron jumps to a distant orbit, and the atom swells thousands of times. These bloated atoms strongly repel each other and cannot be excited simultaneously. In the experiment, a laser pulse traveling at the speed of light nudged one atom. If it became a giant, the second froze — and vice versa. Thus, position entanglement was born: one shifted, the other not, but which one — undetermined.
The distance between possible positions is hundreds of microns. For atoms, it's like separating two people by kilometers. This spatial entanglement promises to be a bridge between stationary quantum elements and flying light particles in future networks.
Original abstract
as written by the authors arXiv:2607.07167
Entanglement between two spatially separate matter particles can be generated via many means and often resides in the internal states of particles. Here, via Rydberg blockade in two spatially separate neutral atoms, we find that the photon recoil in Rydberg excitation can push one atom microns away provided the other atom exerts a state-dependent Rydberg-mediated blockade. When the atoms are recaptured by optical traps, a position-position entangled state between two spatially separate atoms can emerge. This realizes a Bell state of two atoms, where the entanglement exists in the position of each atom and the distance between the two possible locations of each atom can be in the hundred-micron regime.
Between Rydberg atoms, forces act that are comparable to the gravity of small bodies — and this despite their purely electric nature.