Researchers at The University of Manchester have succeeded in observing the so-called Schwinger effect, an elusive process that normally occurs only in cosmic events. By applying high currents through specially designed graphene-based devices, the team - based at the National Graphene Institute - succeeded in producing particle-antiparticle pairs from a vacuum.
Gosh …
… was it in 1980’s ; these proton (+ & -) pairs generated in vacuum with high electric field (?) … searchers expected electron pairs & were surprised with anti-proton signal. (?) or was it theoretical work ? or even a fluke ? Sorry, ref. lost.