[gaze]

The qubits aren't all coupled all the time. The whole point of a 2-qubit gate is the coupling is controllable. Also -- why is the gap of the bare system important? The whole point of QEC is the creation of a decoherence free subspace. Your model is wrong and you don't understand quantum error correction.

[fsh]

The qubits aren't meant to be coupled, but in practice everything is coupled at some level. I find it plausible that having a system with tons of degrees of freedom on a limited energy scale might make it difficult to isolate all the degrees of freedom from each other.

[gaze]

Yeah but these are the most basic of basic problems in QC and people would be discarding approaches that didn’t have potential solutions to this issue. In superconducting QCs, neighboring qubits are not necessarily even resonant, and are in their own little metal boxes. With neutral atoms, you have extremely long lived internal states that barely couple to the environment, and the atoms are macroscopic distances from each other.