A readout shift moves the observed index away from the base by a fixed amount, then a threshold rule turns that index into a classical bit. The base index 8 plus shift 2 gives observed index 10, which meets threshold 9 and yields result bit 1 exactly for the stated ideal readout model; real readout has calibration drift, linewidth, noise, fabrication spread, loss, thermal photons, crosstalk, and readout uncertainty.
A readout shift becomes a classical bit by an exact threshold rule. Exact arithmetic here means exact results for the stated model inputs; measured inputs still carry uncertainty and significant-figure limits.
highlighted = computed this step
A state shift moves the resonator index
The base index is 8 and the shift is 2, so the observed index is 10.
8+2=10
Above the threshold reads bright
The threshold is 9. Observed index 10 reads bright, so the result bit is 1.