Random Telegraph Signal in the Photoluminescence Intensity of a Single Quantum Dot

We propose a model in which the time dependence of the photoluminescence intensity of a single nanosize quantum dot under cw excitation conditions shows a sequence of ``on'' and ``off'' periods similar to a random telegraph signal. In our model the off periods are the times when the dot is ionized and the luminescence is quenched by nonradiative Auger recombination. The duration of the on periods depends on the ionization rate of the dot via thermal or Auger autoionization, and depends strongly on excitation intensity. Numerical simulations reproduce the random intermittency recently observed in the photoluminescence intensity of a single CdSe quantum dot.