Neutral Atom “Flying Qubits” for Fast, Deterministic, Modular Trapped Ion Quantum Computing

We propose to use a single neutral atom (Li) trapped in an optical dipole tweezer trap as a flying qubit to deterministically distribute entanglement between trapped ion (Ba+) quantum computing modules. Our proposed protocol is as follows: By bringing a tweezer-trapped atom close to a trapped ion in a small (30-ion) chain serving as a module of a larger quantum computer, an entangled state is generated 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 connecting the two separate chains. The optical dipole tweezer trap for the neutral atom does not measurably affect the trapped ions, while the RF ion trap does not affect the neutral atom in the tweezer trap. Thus, the neutral atom can be a versatile tool for entangling trapped ions both within an individual ion chain and between distant ion chains, within the same vacuum system, over distances up to several millimeters. With realistic dipole trap parameters, the neutral atom can be moved over 1mm distance in a few tens of microseconds, thus enabling a remote entanglement generation rate of over 1 kHz with modest assumptions, and potentially a few kHz or higher, which is more than an order of magnitude higher than current state-of-the-art.

By combining the best of both atomic worlds we can pave the way to scaling the modular quantum processor arrays with this deterministic atomic qubit remote entanglement, rather than probabilistic/heralded photon-based entanglement. This eliminates the need for multiple trapped ion species and complicated photonic interconnects while offering a higher rate for connection between the modules, comparable to the rate of intra-module entanglement. The neutral atom qubit may also be used to entangle the trapped ion qubits within the individual modules, offering a new paradigm for trapped ion/trapped atom quantum computing architecture.