International audienceThis paper focuses on the notion of " experience " in participatory democracy. The analyis is based on the case of nanotechnology, a domain where the uncertainty about both the objects and publics makes visible two modalities of the democratic experience. On the one hand, the experience as an assemblage where technical and social realities are uncertain. On the other hand, the experience connected to expertbased " technologies of democracy ". Going from one modality to the other requires to pass replication trials, within which technologies of democracy are separated from the particularities of the situations where they areapplied. This approach displays the operations that produce democratic legitimacy, while also ope...