Entanglement of neutral-atom chains by spin-exchange Rydberg interaction

Conditions to achieve an unusually strong Rydberg spin-exchange interaction are investigated and proposed as a means to generate pairwise entanglement and realize a SWAP-like quantum gate for neutral atoms. Ground-state entanglement is created by mapping entangled Rydberg states to ground states using optical techniques. A protocol involving SWAP-gate and pairwise entanglement operations is predicted to create global entanglement of a chain of N atoms in a time that is independent of N.