 Solution

ID: past-exam-of-the-mathematics-course-of-the-university-of-cambridge/2026/iii/paper-323/1/a/ii/solution

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

T (ρ) = j \sum K_{j} ρ K_{j}^{†}, j \sum K_{j}^{†} K_{j} = I .

The second identity is precisely trace preservation. Different Kraus families related by an isometry represent the same channel.

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