A detuning tolerance source scan holds the candidate distance fixed and varies only the tolerance, so the accepted bit flips when the tolerance reaches the distance. With candidate square 2 and target 1, the distance is 1; tolerances 1/2, 1, and 2 give accepted bits 0, 1, and 1 exactly for the stated toy detuning ledger; real devices depend on microwave calibration, resonator drift, flux noise, fabrication spread, and finite-shot uncertainty.
The same detuning distance is compared with three exact tolerance sources. Exact arithmetic here means exact results for the stated model inputs; measured inputs still carry uncertainty and significant-figure limits.
highlighted = computed this step
Tolerance row 1 gives detuning bit 0
The candidate square stays 2 and the distance from target stays 1. The tolerance source is 1/2.
∣2−1∣=1,t=21,a=0
Tolerance row 2 gives detuning bit 1
The candidate square stays 2 and the distance from target stays 1. The tolerance source is 1.
∣2−1∣=1,t=1,a=1
Tolerance row 3 gives detuning bit 1
The candidate square stays 2 and the distance from target stays 1. The tolerance source is 2.
∣2−1∣=1,t=2,a=1
Tolerance is the boundary source
The distance is fixed. Below the distance rejects; equality and larger tolerance accept.