 Solution

ID: past-exam-of-the-mathematics-course-of-the-university-of-cambridge/2026/ii/paper-4/34e/b/solution

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

π = p - q A

gives

[π_{x}, π_{y}] = i q ℏ B

. Hence

[ρ_{x}, ρ_{y}] = i ℏ/ (qB)

and

[R_{x}, R_{y}] = - i ℏ/ (qB)

(with signs reversed together if conventions change); all mixed

[R_{i}, ρ_{j}]

vanish.

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