Density matrix for a mesoscopic current ribbon

TL;DR

This paper introduces a density matrix framework for describing a mesoscopic current-carrying system as an equilibrium state with a modified Hamiltonian, providing a new approach to analyze steady currents.

Contribution

It presents a novel density matrix formulation for mesoscopic systems with steady currents, linking nonequilibrium states to equilibrium systems with constrained Hamiltonians.

Findings

Density matrix of current-carrying system equals that of an equilibrium system with a constrained Hamiltonian.

Provides a theoretical basis for analyzing mesoscopic currents using equilibrium statistical mechanics.

Shows that steady currents can be represented without explicit nonequilibrium conditions.

Abstract

We consider an ideal mesoscopic ribbon in which a steady azimuthal current is generated. We show that the closed interacting electron system in the presence of the current is described by a density matrix which is that of an equilibrium system without current but with a constrained Hamiltonian.