Magnetic field induced rearrangement of the vacuum charge in a graphene quantum dot with a mass gap

A graphene quantum dot provides a solid state analogue of the as yet unobserved charged vacuum predicted by quantum electrodynamics. The magnetic field affects the energy levels that contribute to the vacuum charge and either discharges a vacuum that is already charged or adds charge to it, depending on the position of the affected level relative to the Fermi level. These effects occur in external potentials of a few hundred meV and magnetic fields of a few T, an experimentally realisable regime.