  We present a study of residence time statistics for $N$ blinking quantum
dots. With numerical simulations and exact calculations we show sharp
transitions for a critical number of dots. In contrast to expectation the
fluctuations in the limit of $N \to \infty$ are non-trivial. Besides quantum
dots our work describes residence time statistics in several other many
particle systems for example $N$ Brownian particles. Our work provides a
natural framework to detect non-ergodic kinetics from measurements of many
blinking chromophores, without the need to reach the single molecule limit.
