Neutral-Atom Qubits
Neutral-atom qubits hold single atoms in optical tweezers and entangle them through Rydberg states, combining uniformity with flexible geometry.
Atoms in light
A neutral-atom processor traps individual atoms, often rubidium or cesium, in tightly focused laser beams called optical tweezers. Because the atoms are neutral, they do not repel each other, so hundreds can be arranged in dense two- or three-dimensional patterns. As with ions, every atom of a species is identical, giving natural qubit uniformity.
Qubit encoding
The qubit usually lives in two hyperfine ground states, which are long-lived and controlled by microwaves or two-photon Raman transitions. Atoms are first loaded stochastically into a tweezer array, then rearranged atom-by-atom into a defect-free pattern using movable tweezers, a step that makes reliable arrays from a random initial load.
Rydberg entanglement
Two ground-state atoms do not interact, so entangling gates promote atoms to highly excited Rydberg states, which have giant electric dipoles. The Rydberg blockade means one excited atom shifts a nearby atom's energy so a second excitation is forbidden, creating a conditional interaction that implements a two-qubit gate within a blockade radius of a few micrometers.
Distinctive strengths
- Reconfigurable connectivity: atoms can be physically moved to bring any pair together
- Large qubit counts, with arrays of hundreds already demonstrated
- A native fit to analog quantum simulation of many-body physics
Challenges include finite Rydberg-state lifetime, atom loss during operation, and laser intensity noise. Neutral atoms have advanced quickly and are strong for both gate-model and analog-simulation work, with movable qubits offering a route around fixed-lattice routing limits.