  We entangle two co-trapped atomic barium ion qubits by collecting single
visible photons from each ion through in-vacuo 0.8 NA objectives, interfering
them through an integrated fiber-beamsplitter and detecting them in
coincidence. This projects the qubits into an entangled Bell state with an
observed fidelity lower bound of F > 94%. We also introduce an ytterbium ion
for sympathetic cooling to remove the need for recooling interruptions and
achieve a continuous entanglement rate of 250 1/s.
