Negative index of refraction in a four-level system with magnetoelectric cross coupling and local field corrections

TL;DR

This paper demonstrates how a coherently driven four-level atomic system can achieve a negative index of refraction with low absorption by utilizing magnetoelectric cross coupling and local field effects, with potential applications in metamaterials.

Contribution

It introduces a novel four-level atomic scheme that incorporates magnetoelectric cross coupling and local field corrections to realize negative refraction.

Findings

Negative index achieved with low absorption

Dependence on number density and control field ratio

Negative refraction over a range of probe detunings

Abstract

This research focuses on a coherently driven four-level atomic medium with the aim of inducing a negative index of refraction while taking into consideration local field corrections as well as magnetoelectric cross coupling, i.e. chirality, within the material's response functions. Two control fields are used to render the medium transparent for a probe field which simultaenously couples to an electric and a magnetic dipole transition, thus allowing one to test the permittivity and permeability of the material at the same time. Numerical simulations show that a negative index of refraction with low absorption can be obtained for a range of probe detunings while depending on number density and the ratio between the intensities of the control fields.