Coherent superposition of emitted and resonantly scattered photons from a two-level system driven by an even-$\pi$ pulse

Abstract

We report the observation of a bunching of ~3 photon states, which is a coherent superposition of emitted photons and resonantly scattered laser photons, arising upon excitation by even-$\pi$ pulses of a two-level system represented by a charged quantum dot in a microcavity. This phenomenon emerges because the exciting laser pulse contains several tens of photons whose quantum amplitude distribution creates such a superposition, and the polarization of the scattered photons is changed by the interaction with the charged resonant system. Such a beam is a high-order member of the Fock space, promising for quantum technologies.