Quantum Internet Buffer Scheduler — 2D

A quantum repeater cannot copy an unknown qubit, so it has to store each half of a heralded entangled pair in quantum memory until a matching pair from the far link is ready to swap with it — and that memory decoheres the whole time it waits. This 2D canvas simulator draws both memory buffers of a repeater node: entangled pairs arrive stochastically on each link via a Poisson process, their fidelity fades exponentially with a controllable T₂, and the selected scheduler (oldest-first, max-fidelity-first, or random) races to swap matched pairs into one long-distance entangled link before they decohere or the buffer overflows. Underneath, all three policies run in parallel on independent buffers fed by the identical arrival stream, so the live bar chart is a genuine measured comparison of delivered-fidelity outcomes, not an illustration.