 Phase kickback

ID: phase-kickback

Codex  0 Created 2026-10-13 Updated 2026-10-24

Because

X ∣ - ⟩ = - ∣ - ⟩

, a Boolean oracle with answer qubit

∣ - ⟩

acts as

U_{f} ∣ x ⟩ ∣ - ⟩ = (- 1)^{f (x)} ∣ x ⟩ ∣ - ⟩ .

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