S-Matrix Poles Close to Thresholds in Confined Geometries

TL;DR

This paper investigates how S-matrix poles near thresholds behave in quantum waveguides with cavities and defects, explaining conductivity changes through pole transitions.

Contribution

It reveals the dynamics of dominant and shadow poles near thresholds and their impact on conductivity in confined quantum systems.

Findings

Identification of dominant and shadow poles on different Riemann sheets

Explanation of conductivity variations via pole transitions

Analysis of how cavity width influences pole behavior

Abstract

We have studied the behavior of the S-matrix poles near threshold for quantum waveguides coupled to a cavity with a defect. We emphasize the occurrence of both dominant and shadow poles on the various sheets of the energy Riemann surface, and show that the changes of the total conductivity near threshold as the cavity's width changes can be explained in terms of dominant to shadow pole transitions.