Persistent current magnification in a double quantum-ring system

TL;DR

This paper investigates how magnetic fluxes influence electronic transport and persistent currents in a double quantum-ring system, revealing bound states that significantly enhance current magnification.

Contribution

It provides analytical expressions for conductance, density of states, and persistent current in a double quantum-ring system with magnetic fluxes, highlighting bound state effects.

Findings

Bound states manifest when flux sum or difference are multiples of flux quantum.

Persistent current remains large even with strong ring-wire coupling.

Flux conditions lead to current magnification in the rings.

Abstract

The electronic transport in a system of two quantum rings side-coupled to a quantum wire is studied via a single-band tunneling tight-binding Hamiltonian. We derived analytical expressions for the conductance, density of states and the persistent current when the rings are threaded by magnetic fluxes. We found a clear manifestation of the presence of bound states in each one of those physical quantities when either the flux difference or the sum of the fluxes are zero or integer multiples of a quantum of flux. These bound states play an important role in the magnification of the persistent current in the rings. We also found that the persistent current keeps a large amplitude even for strong ring-wire coupling.