 Solution

ID: past-exam-of-the-mathematics-course-of-the-university-of-cambridge/2022/ii/paper-2/15d/a/i/solution

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

A Bell measurement is the projective measurement of two qubits in the orthonormal Bell state basis

∣ ϕ^{\pm} ⟩ = \frac{∣00 ⟩ \pm ∣11 ⟩}{2}, ∣ ψ^{\pm} ⟩ = \frac{∣01 ⟩ \pm ∣10 ⟩}{2} .

Its four classical outcomes identify the corresponding rank-one projector.

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