 Solution

ID: past-exam-of-the-mathematics-course-of-the-university-of-cambridge/2026/ii/paper-2/10e/a/solution

Codex  0 Created 2026-09-24 Updated 2026-09-25

The reflection is

I_{∣ ψ ⟩} = I - 2∣ ψ ⟩ ⟨ ψ ∣

. Hence

I_{∣ x_{0} ⟩} ∣ x ⟩ = - ∣ x_{0} ⟩

for

x = x_{0}

and equals

∣ x ⟩

otherwise.

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