One of the biggest problems with superconducting QCs is qubit connectivity. Ideally you want to be able to have all-to-all connectivity, because you want to app

One of the biggest problems with superconducting QCs is qubit connectivity. Ideally you want to be able to have all-to-all connectivity, because you want to apply multi-qubit gates on any subset of qubits. With superconducting QCs, qubits are literally connected physically with (kind of) wires. Each connector is another qubit-like component which is driven by classical analog instrument, which again requires a wire going into the chip. It's basically impossible in practice to build a fully connected 100 qubit chip today, for example. I don't know a lot about photonic QCs, but it at least "solves" this issue: you can apply a signal on multiple qubits at once and you don't need to build a physical connection between them. You also don't need near absolute zero temperatures. EDIT: sorry, I was thinking of trapped-ion QCs, not photonic! The company I work at is developing (among other things) chips with a so-called computational resonator[1]: think of a long "bus" to which multiple qubits are connected. As a result, you essentially get all-to-all connectivity with intermediate state moves. 1. https://www.iqmacademy.com/learn/deneb/01-move/ https://www.iqmacademy.com/learn/deneb/01-move/