HBT Coincidence Trace 2D — Single-Photon Purity g²(0)

The same Monte-Carlo Hanbury Brown–Twiss photon statistics as the 3D quantum-dot lab, rendered as the data actually looks on real time-tagged photon-counting hardware: a scrolling two-lane detector click trace with same-pulse coincidences highlighted, and a live g²(τ) coincidence histogram built from the running correlation sums. Tune the dot's multi-photon probability and detector dark-count rate to watch antibunching degrade, then engage the heralding time-gate to see background clicks thin out faster than genuine ones — the real efficiency-vs-purity trade-off used to certify single-photon sources.