Spin-to-OAM Converter: 2D Phase-Wheel & Beam View

Quantum information doesn't only need to move between systems — it sometimes needs to change the physical degree of freedom that carries it. This simulator models a q-plate, a real photonic device that converts a photon's polarization (spin angular momentum) qubit into orbital angular momentum, the helical twist of its wavefront. Prepare an input photon anywhere between pure |L⟩, pure |R⟩ and a balanced linear superposition, tune the plate's topological charge q and retardance δ, then fire photons one at a time or as a stream. A schematic beam-path panel shows each photon either passing straight through unconverted or spiralling out on a helix with q full twists, while a draggable orbital-angular-momentum phase wheel renders the actual e^iℓφ helical wavefront of the outcome. Live readouts compare the theoretical conversion probability sin²(δ/2) against the measured trial average and track a spin–orbit coupling indicator that shows exactly when partial conversion correlates a photon's polarization with the path it took — the same physics behind hybrid vector-vortex beams used in orbital-angular-momentum quantum communication.