Bound states in the continuum driven by AC fields

TL;DR

This paper demonstrates the creation of bound states in the continuum within a quantum ring system driven by AC fields, revealing Fano resonances and localized states controllable via an AC side-gate voltage.

Contribution

It introduces a model for bound states in the continuum induced by time-periodic AC fields in a quantum ring setup, with detailed analysis of transmission and density of states.

Findings

Fano resonance observed at specific energies

Local density of states peaks sharply indicating bound states

Bound states approach Dirac delta in weak coupling limit

Abstract

We report the formation of bound states in the continuum driven by AC fields. This system consists of a quantum ring connected to two leads. An AC side-gate voltage controls the interference pattern of the electrons passing through the system. We model the system by two sites in parallel connected to two semi-infinite lattices. The energy of these sites change harmonically with time. We obtain the transmission probability and the local density of states at the ring sites as a function of the parameters that define the system. The transmission probability displays a Fano profile when the energy of the incoming electron matches the driving frequency. Correspondingly, the local density of states presents a narrow peak that approaches a Dirac delta function in the weak coupling limit. We attribute these features to the presence of bound states in the continuum.