Optically gated resonant emission of single quantum dots.

We report on the resonant emission in coherently driven single semiconductor quantum dots. We demonstrate that an ultraweak nonresonant laser acts as an optical gate for the quantum dot resonant response. We show that the gate laser suppresses Coulomb blockade at the origin of a resonant emission quenching, and that the optically gated quantum dots systematically behave as ideal two-level systems in both regimes of coherent and incoherent resonant emission.