Persistent currents through a quantum impurity: Protection through integrability

TL;DR

This paper demonstrates that in an integrable one-dimensional mesoscopic ring with a magnetic impurity, the persistent current remains unaffected by the impurity due to the system's integrability, as shown through Bethe Ansatz analysis.

Contribution

It provides a symmetry-based analysis showing persistent current protection in integrable impurity-electron systems, independent of physical parameters.

Findings

Persistent current is insensitive to magnetic impurity in the integrable model

Bethe Ansatz solution reveals symmetry-based protection

Protection mechanism is general for integrable impurity-electron interactions

Abstract

We consider an integrable model of a one-dimensional mesoscopic ring with the conduction electrons coupled by a spin exchange to a magnetic impurity. A symmetry analysis based on a Bethe Ansatz solution of the model reveals that the current is insensitive to the presence of the impurity. We argue that this is true for any integrable impurity-electron interaction, independent of choice of physical parameters or couplings. We propose a simple physical picture of how the persistent current gets protected by integrability.