Fermonnummerstroom

Fermonnummerstroom is a term used in some Dutch-language discussions to denote the flow of fermion number in a physical system. It describes how the count of fermionic particles crosses a boundary or region over time, and is closely related to the concept known in English as fermion number current or charge current.

Etymology and usage: The compound combines nummer meaning number and stroom meaning flow, with fermon as the root for fermion, reflecting its focus on fermionic quanta. The term is commonly encountered in quantum transport, mesoscopic physics, and lattice simulations where tracking the transfer of fermions across interfaces is important.

Theoretical basis: In many-body quantum mechanics, the number operator N counts fermions. Its time evolution is governed by the continuity equation, which relates the time rate of change of N in a region to the net fermonnummerstroom across the region's boundary. In relativistic quantum field theory, the fermonnummerstroom corresponds to a conserved current associated with a U(1) symmetry, and can be affected by anomalies in certain contexts.

Measurement and applications: The fermonnummerstroom can be inferred from transport measurements in nanoscale devices such as quantum dots, quantum point contacts, or cold-atom simulators. It is used to analyze nonequilibrium steady states, charge pumping, and information flow in quantum systems, as well as to study decoherence and interaction effects on fermionic currents.

See also: fermion current; number operator; quantum transport; continuity equation.