 Solution

ID: past-exam-of-the-short-options-paper-of-the-physics-prelims-of-the-university-of-oxford/2022/s03/2/b/ii/solution

S_{x}

. The inputs are its orthogonal eigenstates, so

p (x + ∣ ψ_{+}) = 1, p (x + ∣ ψ_{-}) = 0.

The output beam identifies the input with certainty in a single ideal measurement.

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