  An electrical current that flows across individual atoms or molecules can
generate exotic quantum-based behavior, from memristive effects to Coulomb
blockade and the promotion of quantum excited states. These fundamental effects
typically appear one at a time in model junctions built using atomic tip or
lateral techniques. So far, however, a viable industrial pathway for such
discrete state devices has been lacking. Here, we demonstrate that a
commercialized device platform can serve as this industrial pathway for quantum
technologies. We have studied magnetic tunnel junctions with a MgO barrier
containing C atoms. The paramagnetic localized electrons due to individual C
atoms generate parallel nanotransport paths across the micronic device as
deduced from magnetotransport experiments. Coulomb blockade effects linked to
tunnelling magnetoresistance peaks can be electrically controlled, leading to a
persistent memory effect. Our results position MgO tunneling spintronics as a
promising platform to industrially implement quantum technologies.
