QDOM project bridges the gap, at the nanoscale, between two yet distinct research fields: optomechanics of deformable cavities (« Cavity Optomechanics ») and cavity Quantum ElectroDynamics (« Cavity QED »). These two fields utilize an electromagnetic wave trapped in a cavity, to boost its interaction with a mechanical oscillator (in optomechanics) or with an atom (in cavity QED). QDOM project aims at exploring a hybrid interface between these two domains, using semiconductor nanostructures. Indeed, semiconductor nano-optomechanical systems have advanced rapidly over the last three years, showing record optomechanical coupling, mechanical frequencies above the GHz, and a well controlled optical and mechanical dissipation. In parallel, semiconductor Quantum Dots (QD), notably Indium Arsenide QDs in a Gallium Arsenide matrix, have made impressive progress in solid-state cavity QED: the realization of non-classical photon sources, the strong coupling regime of cavity QED, and the observation of giant non-linearity at the single photon level. QDOM project exploits all these advances of semiconductor nanostructures: indeed the chosen experimental system is a miniature GaAs disk cavity that possesses a sub-micron optical mode volume. The whispering gallery modes sustained by the structure are of very high quality factor and enable a coupling of the cavity photons both to the GHz mechanical modes of the disk and to a single InAs QD inserted into the disk. The record optomechanical coupling reached in the structure is combined with the possibility of strong coupling of the QD to the cavity mode, making miniature GaAs disks a unique platform for Quantum Dot Optomechanics. In this novel field of research proposed by the project, the aim is to control a coupled tri-partite system: a cavity photon interacts with a coherent quantum emitter (two-level atom) and with a single mechanical mode. QDOM project seeks at inspecting this novel physics paradigm, both experimentally and theoretically. The partners will first optimize the on-chip design and optomechanical properties of GaAs disk resonators embedding InAs Quantum Dots. A second part of the project aims at controlling the QD dephasing mechanisms in a cavity to amplify the QD impact in optomechanical phenomena, and then proposes to develop resonant spectroscopy experiments on a single QD coupled to a GaAs disk cavity mode. At that point first optomechanics experiments relying on the coupling to a Quantum Dot will be performed: the observation of QD-assisted optomechanical dynamical back-action, leading to the QD-assisted control of the disk mechanical motion, and then the modification by the disk mechanical motion of the resonant optical response of a QD in a cavity. These experimental developments will be carried-out in parallel with theoretical developments that aim, with a growing level of refinement, at a quantum description of the QD-optomechanics situations under study. The project involves two laboratories and brings together three teams with complementary internationally recognized expertise: an expert team in semiconductor nano-optomechanics (MPQ), an expert team in Quantum Dot cavity QED (LPN), and an expert theory team in semiconductor quantum electrodynamics and optics (MPQ). All conditions are thus met to advance in the novel nanoscience research line proposed by the project.