Quantum Dot FRET Cascade — 2D Energy Ladder

This simulator visualises the same Förster resonance energy transfer (FRET) relay as the 3D cascade, but as two native 2D diagrams: a live E(r) = 1/(1+(r/R₀)⁶) efficiency-vs-distance curve, and a four-rung energy-level ladder where each pumped exciton stochastically either steps down to the next quantum dot or falls off the ladder (radiative decay), with the real transfer rate k_FRET = (1/τ_D)·(R₀/r)⁶ racing against donor decay 1/τ_D at every rung. Tune the dot spacing, Förster radius and donor lifetime to see how a few nanometres of separation move the marker along the efficiency curve and change how often excitons survive all the way down the ladder — watch the measured cascade efficiency converge toward the theoretical E³ prediction as more excitons are pumped through.