Localization of interacting electrons in quantum dot arrays driven by an ac-field

TL;DR

This paper explores how ac-fields influence two interacting electrons in quantum dot arrays, revealing regimes of tunneling suppression and electron binding, with implications for controlling electron localization.

Contribution

It demonstrates how ac-fields can induce coherent destruction of tunneling and electron binding in quantum dot arrays, explained through Floquet quasienergy analysis.

Findings

Coherent destruction of tunneling occurs at specific ac-field frequencies.

Electrons can form a bound state despite strong Coulomb repulsion.

Control of electron localization via ac-field parameters is demonstrated.

Abstract

We investigate the dynamics of two interacting electrons moving in a one-dimensional array of quantum dots under the influence of an ac-field. We show that the system exhibits two distinct regimes of behavior, depending on the ratio of the strength of the driving field to the inter-electron Coulomb repulsion. When the ac-field dominates, an effect termed coherent destruction of tunneling occurs at certain frequencies, in which transport along the array is suppressed. In the other, weak-driving, regime we find the surprising result that the two electrons can bind into a single composite particle -- despite the strong Coulomb repulsion between them -- which can then be controlled by the ac-field in an analogous way. We show how calculation of the Floquet quasienergies of the system explains these results, and thus how ac-fields can be used to control the localization of interacting electron systems.