Tunable quantum interference effects in Floquet two- and three-level systems

TL;DR

This paper explores tunable quantum interference effects in periodically modulated Floquet two- and three-level systems, revealing new phenomena like multipeak spectra, controllable transparency windows, and asymmetric interference effects, expanding understanding beyond traditional unmodulated systems.

Contribution

It provides analytical and numerical analysis of quantum interference in Floquet systems, demonstrating tunable transparency windows and new interference effects not seen in unmodulated systems.

Findings

Demonstration of coherent destruction tunneling in Floquet two-level systems.

Identification of multiple tunable transparency windows in Floquet three-level systems.

Discovery of asymmetric quantum interference windows distinct from traditional EIT and ATS.

Abstract

Quantum interference effects in the unmodulated quantum systems with light-matter interaction have been widely studied, such as electromagnetically induced transparency (EIT) and Autler-Townes splitting (ATS). However, the similar quantum interference effects in the Floquet systems (i.e., periodically modulated systems), which might cover rich new physics, were rarely studied. In this article, we investigate the quantum interference effects in the Floquet two- and three-level systems analytically and numerically. We show a coherent destruction tunneling effect in a lotuslike multipeak spectrum with a Floquet two-level system, where the intensity of the probe field is periodically modulated with a square-wave sequence. We demonstrate that the multipeak split into multiple transparency windows with tunable quantum interference if the Floquet system is asynchronously controlled via a third level. Based on phenomenological analysis with Akaike information criterion, we show that the symmetric central transparency window has a similar mechanism to the traditional ATS or EIT depending on the choice of parameters, additional with an extra degree of freedom to control the quantum interference provided by the modulation period. The other transparent windows are shown to be asymmetric, different from the traditional ATS and EIT windows. These nontrivial quantum interference effects open up a scope to explore the applications of the Floquet systems.