Persistent current in a ring coupled to an external fermionic reservoir

TL;DR

This paper investigates how coupling a mesoscopic ring to a fermionic reservoir affects its energy spectrum and persistent current, revealing conditions under which the current persists despite strong coupling.

Contribution

It introduces a detailed analysis of the energy spectrum and persistent current in a ring-reservoir system, highlighting the emergence of quasistates with sharp eigenenergies.

Findings

Persistent current is generally suppressed by tunneling.

Increasing coupling alters the level structure and can sustain a nonzero current.

Quasistates with sharp eigenenergies develop at strong coupling.

Abstract

We study the energy spectrum and the persistent current in an ideal one-dimensional mesoscopic ring coupled to a fermionic reservoir. We find that the tunnel coupling in general leads to the suppression of the persistent current. However, with increasing coupling, the effective level structure of the ring coupled to the reservoir changes and quasistates with a sharp eigenenergy develop. Depending on the number of ring states coupled to the reservoir this results in a nonzero persistent current even at very large tunneling between the ring and the reservoir.