Comment by adastra22
2 hours ago
Transistors connect to other transistors, directly or in switched arrangements. Qubits can be connected to other qubits likewise. E.g. a single photon emitter next to a nuclear spin qubit that can send an entangled photon through a beam splitter in a photonic switch, routing that entangled pair through fiber optic cables to other qubits where a combination of electric fields, filters, and occupied energy levels cause gate operations to be applied during absorption & re-emission. Except for the long-lived, error-corrected qubit, everything I described there is off-the-shelf commercial technology.
Photonic quantum interfaces typically operate at glacial speeds and with terrible fidelities. There is a lot more missing than good qubits.