Features of level broadening in a ring-stub system

TL;DR

This paper investigates how anti-resonances in a ring-stub system influence level broadening when coupled to an electron reservoir, revealing effects on pole distribution and implications for disordered systems under magnetic flux.

Contribution

It demonstrates that anti-resonances limit level broadening in a ring-stub system and affect pole distribution under magnetic flux variations, providing new insights into quantum transport phenomena.

Findings

Anti-resonances limit level broadening in the system.

Anti-resonances anchor the poles when magnetic flux varies.

Differences in broadening are shown by comparison to an infinite reservoir.

Abstract

When a one dimensional (1D) ring-stub system is coupled to an electron reservoir, the states acquire a width (or broadening characterized by poles in the complex energy plane) due to finite life time effects. We show that this broadening is limited by anti-resonances due to the stub. The differences in level broadening in presence and absence of anti-resonance is exemplified by comparison to a 1D ring coupled to an infinite reservoir. We also show that the anti-resonances due to the stub has an anchoring effect on the poles when a magnetic flux through the ring is varied. This will have implication on change in distribution of the poles in disordered multichannel situation as magnetic flux is varied.