Neutral Atoms in Optical Tweezers as Messenger Qubits for Scaling up a Trapped Ion Quantum Computer

Abstract: We propose to combine neutral atom and trapped ion qubits in one scalable modular architecture that uses shuttling of individual neutral atoms in optical tweezers to realize atomic interconnects between trapped ion quantum registers. These interconnects are deterministic, and thus may be performed on-demand. The proposed protocol is as follows: a tweezer-trapped neutral atom qubit is brought close to a trapped ion in an ion chain serving as a module of a larger quantum computer, and an entangling gate is performed between the two qubits. Then the neutral atom is quickly moved to another, nearby trapped ion chain in the same modular ion trap and entangled with an ion in that chain, thus entangling the two separate ion chains. The optical dipole potential of the tweezer beam for the neutral atom does not measurably affect the trapped ions, while the RF ion trap does not affect the neutral atom. With realistic tweezer trap parameters, the neutral atom can be moved over millimeter scale distance in a few tens of microseconds, thus enabling a remote entanglement generation rate of over 10^3/s even with very modest assumptions for the atom-ion quantum gate speed, and possibly up to 10^4/s, which is two orders of magnitude higher than the current state-of-the-art with photonic interconnects.