Atoms Get Entangled in Space: A New Kind of Quantum Link ⚡ экспресс
Physicists used Rydberg blockade (a phenomenon where excitation of one atom prevents excitation of a neighbor) and photon recoil (a laser kick) to entangle the positions of two neutral atoms. When one atom shifts due to the kick, the other, thanks to the blockade, stays put, but their coordinates become correlated. After trapping, a Bell state emerges where each atom has some probability of being in one of two locations, separated by up to hundreds of microns. This result is remarkable because macroscopic separation of entangled particles opens new possibilities for quantum technologies.
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.
🎯 Between Rydberg atoms, forces act that are comparable to the gravity of small bodies — and this despite their purely electric nature.