Magnetic field controlled vacuum charge in graphene quantum dots with a mass gap

TL;DR

This paper explores how magnetic fields influence vacuum charge in graphene quantum dots with a mass gap, revealing re-entrant charging cycles observable at laboratory magnetic field strengths.

Contribution

It demonstrates that magnetic field effects on vacuum charge, previously only seen in astrophysical contexts, can be realized in graphene quantum dots at laboratory fields, providing a solid-state model of charged vacuum phenomena.

Findings

Magnetic field induces jumps in vacuum charge levels.

Re-entrant vacuum charging cycles occur at laboratory magnetic fields.

Phase diagrams show charge dependence on potential and magnetic field.

Abstract

The effect of a magnetic field on the charged vacuum is investigated. The field dependence of the energy levels causes jumps in the total vacuum charge that occur whenever an energy level crosses the Fermi level and this leads to re-entrant cycles of vacuum charging and discharging. In atomic systems these effects require astrophysical magnetic fields of around 10^8 T but in graphene with a mass gap they occur in laboratory fields of about 1 T or lower. It is suggested that an electrostatic graphene quantum dot defined by a gate electrode provides a solid state model of the as yet unobserved charged vacuum as well as a model of an atomic system in an extreme astrophysical environment. Phase diagrams are computed to show how the total vacuum charge depends on the confining potential strength and applied magnetic field. In addition the field dependence of the vacuum charge density is investigated and experimental consequences are discussed.