  Trapped atomic ions are a leading platform for quantum information networks,
with long-lived identical qubit memories that can be locally entangled through
their Coulomb interaction and remotely entangled through photonic channels.
However, performing both local and remote operations in a single node of a
quantum network requires extreme isolation between spectator qubit memories and
qubits associated with the photonic interface. We achieve this isolation and
demonstrate the ingredients of a scalable ion trap network node by co-trapping
$^{171}$Yb$^+\ $ and $^{138}$Ba$^+\ $ qubits, entangling the mixed species
qubit pair through their collective motion, and entangling the $^{138}$Ba$^+\ $
qubits with emitted visible photons.
