Past exam of the mathematics course of the University of Cambridge 2025 ib Paper 4 4C Solution Created 2026-09-23 Updated 2026-09-25
Separation with Dirichlet walls givesFor , the ground state has a nondegenerate energy. The cheapest excitation changes the quantum number in the longest direction, so the first excited state also has a nondegenerate energy.
If , the ground-state energy remains nondegenerate, but and have equal first-excited energy, giving degeneracy two.