Atoms Get Entangled in Space: A New Kind of Quantum Link ⚡ экспресс
Entangling two spatially separated atoms is usually achieved through their internal states. This work shows that in a system of two neutral atoms, separated in space, Rydberg blockade and photon recoil from Rydberg excitation can displace one atom by several microns if the second atom blocks the excitation. After recapturing the atoms with optical tweezers, an entangled state forms where their spatial positions are correlated. The resulting state is a Bell state of two atoms, each in a superposition of two locations separated by up to hundreds of microns. This approach enables the creation of macroscopic entangled states, valuable for quantum information processing.
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.