Residual Drift Scan - Quantum Computing Physical Bases: Control, Coupling, and Error Signals Step by Step

A residual is a counted difference after calibration, not a rewrite of the quantum state. Exact arithmetic here means exact results for the stated model inputs; measured inputs still carry uncertainty and significant-figure limits.

highlighted = computed this step

The audit starts with one calibrated prediction

The calibrated baseline expects 57 zero reads and 23 one reads over 80 shots.

N_{\text{zero}}=57,\quad N_{\text{one}}=23

A small drift is a counted difference

New counts 55 and 25 leave residuals 2 and 2.

\Delta N_{\text{zero}}=2,\quad \Delta N_{\text{one}}=2

Three residual rows separate baseline from drift

The residual rows compare count differences only. They do not change the prepared state, the coupling map, or the readout assignment matrix.

\begin{array}{c|c|c|c}\text{row}&N_{\text{zero}}&N_{\text{one}}&\Delta\\\text{baseline}&57&23&0\\\text{small}&55&25&2\\\text{large}&52&28&5\\\end{array}

A larger residual flags drift without rewriting physics

The larger row has residuals 5 and 5. That is an alarm number, not a new qubit state.

\Delta N_{\text{zero}}=5,\quad \Delta N_{\text{one}}=5