Auger process has been described as a so-called shake-up process in the Fermi-sea [@Skolnick1994; @Manfra1998; @Kleemans2010], a many-particle effect. In an atom-like configuration, the radiative Auger process has not been observed – neither in a few-electron configuration nor in the limit of a single-photon emitter. The prospect of applying quantum optics techniques to determine the dynamics of the electron following a radiative Auger process has not been considered so far.

Here, we measure the radiative Auger process at optical frequencies for the minimum number of two excited electrons. We observe the radiative Auger process for a negative trion (an exciton consisting of two electrons and one hole), which is confined to a zero-dimensional quantum dot (QD) [@Michler2003]. Quantum optics techniques are used to prove that the strong fluorescence and the weak radiative Auger emission come from the same QD, and that the QD emits a photon either at the resonance frequency or at the radiative Auger frequency: the two colours cannot be created simultaneously and there is no time-ordering.

The radiative Auger process promotes the additional (Auger) electron to a higher shell of the QD. No continuum states are involved. The emitted photon is red-shifted by the energy which is 