Sandbox · Fig. 03
2D wave-packet
Quantum dynamics in two dimensions. Pick a scene; a Gaussian wave packet evolves under the Schrödinger equation via split-step Fourier. The bright cloud is |ψ(r, t)|²; walls show as faint outlines.
Free particle spreads as it moves (Heisenberg uncertainty in action). The tunnel-barrier scene shows quantum tunneling: even when the packet's kinetic energy is below the barrier height, some amplitude leaks through. Double slit gives the canonical interference pattern downstream. Harmonic trap orbits stay bounded forever (a coherent state). Circular ring traps the packet on a closed loop.