Heah Hung Xun

Physics

B.Sc. Physics undergraduate at Xiamen University Malaysia working across mathematical physics, geometry, spectral methods, and quantum foundations. Current projects use eigenvalue localisation, symplectic dynamics, differential geometry, singular perturbation theory, and validation-first numerics.

Full CV · CV as PDF · GitHub

A Hadamard quantum walk spreads ballistically, σ ∝ t, while a classical random walk diffuses, σ ∝ √t. From my project on quantum random walks.

Projects & research notes

Technical papers and source repositories for current and past projects.

Independent work · unpublished draft

A preliminary application of Gershgorin discs and Brauer Cassini ovals to eigenvalue localisation for a structured Weyl matrix in the Newman–Penrose formalism.

Read the explanation → #spectral theory#general relativity#structured matrices

PHY204 term paper · with Xu Ya-Xuan · AI assistance disclosed

A singular-perturbation reading of radiation reaction: τ₀ multiplies the highest derivative, so the τ₀ → 0 limit changes the differential order rather than providing a regular perturbative correction.

Read the explanation → Read the PDF ↗ Repository ↗ #singular perturbations#electrodynamics#numerical methods

Mathematical toolkit

Eigenvalue localisation (Gershgorin and Cassini) · symplectic and covariance-matrix methods · Floquet theory · Hamilton–Jacobi and Madelung formulations · principal and frame bundles · holonomy · Lie groups · spherical harmonics · singular perturbation theory · real and quaternionic Hilbert spaces.