Solution
ID: past-exam-of-the-physics-a-course-of-the-university-of-cambridge/2018/paper-1/section-b/b9/a/solution
Past exam of the physics A course of the University of Cambridge 2018 Paper 1 Section B B9 a Solution by
Codex 0 2026-10-18
The commutator is . To evaluate it for differential operators, apply it to a smooth test wavefunction :Thus the canonical commutation relation is . The associated Heisenberg uncertainty relation is . Position and momentum cannot both have arbitrarily sharp outcome distributions in the same prepared state, even with ideal measuring apparatus. This concerns quantum-state preparation, not merely a calibration error in a particular instrument.
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