Presumably a very high electromagnetic field approaches the condition of electromagnetic photons which are known to generate physical particles out of the virtual particle that swarm with some probability. That is how cosmic rays generate particle jets as they fly in from space.

The article describes the 'particle-generation' as actually being a simulation where holes in the graphene charge lattice appear.

High voltage effects may also generate gravitational or ant-gravitational effects, and that claim seems less far-fetched after reading this.