Quantum Dot Re-excitation — Pulsed g²(τ) Comb

A pulsed quantum dot single-photon source is only as good as its second-order correlation function g²(τ): an ideal emitter fires exactly one photon per laser pulse, so the Hanbury Brown–Twiss coincidence histogram it produces is a comb of peaks with the central one, at zero delay, missing entirely. This simulator drives a quantum dot with a periodic pulse train, splits its emission on a 50/50 beamsplitter toward two detectors, and builds that g²(τ) comb live from real click statistics — while two of the mechanisms that actually degrade single-photon purity in the lab, re-excitation within a pulse and detector background counts, are exposed as sliders you can push until the central dip fills back in. Live readouts turn the histogram into a numeric g²(0) estimate and a single-photon purity percentage, exactly how the measurement is reported in quantum-optics papers.