Bit-Flip and Phase-Loss Budgets

Bit And Phase Budgets Stay Separate

different checked surfaces

Bit errors change population counts, while phase errors reduce a visibility signal; those are different checked surfaces. The exact 80/20 and coherent-fraction ledgers make the comparison audit-friendly, but measured devices need separate calibrations before the two budgets can be trusted.

Population motion and phase visibility are different exact budgets. 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 bit-flip budget changes population counts

The population channel changes the state ledger from 100 zero shots to 80 zero and 20 one.

N⃗bit=(80,20)\vec N_{\text{bit}}=(80,20)
Population changeThe bit-flip channel moves counts between labels.1zero0one4/5zero1/5onechannel map

A phase-loss budget changes visible signal instead

The phase-loss budget keeps the question as visibility: 50 ideal visible counts reduce to 30 visible counts.

Nvisible=30N_{\text{visible}}=30
Separate phase budgetPhase loss is not relabeled as a bit flip.3/5coherent2/5dephasedphase loss