  Quantum processing architectures that include multiple qubit modalities offer
compelling strategies for high-fidelity operations and readout, quantum error
correction, and a path for scaling to large system sizes. Such hybrid
architectures have been realized for leading platforms, including
superconducting circuits and trapped ions. Recently, a new approach for
constructing large, coherent quantum processors has emerged based on arrays of
individually trapped neutral atoms. However, these demonstrations have been
limited to arrays of a single atomic element where the identical nature of the
atoms makes crosstalk-free control and non-demolition readout of a large number
of atomic qubits challenging. Here we introduce a dual-element atom array with
individual control of single rubidium and cesium atoms. We demonstrate their
independent placement in arrays with up to 512 trapping sites and observe
negligible crosstalk between the two elements. Furthermore, by continuously
reloading one atomic element while maintaining an array of the other, we
demonstrate a new continuous operation mode for atom arrays without any
off-time. Our results enable avenues for ancilla-assisted quantum protocols
such as quantum non-demolition measurements and quantum error correction, as
well as continuously operating quantum processors and sensors.
