Logical qubit

A logical qubit is the protected choice a long calculation is meant to use, spread across many physical qubits on the chip. A scrambled phase or a flipped bit can be noticed and repaired among the physical qubits without a measurement that would spend the logical state.

The noise note leaves the count of physical qubits per logical one to the courses next door. The bedroom diagram still has one wire, and that wire is where the phase is learned before anyone draws the pile of hardware to scale.