Magnetic response enhancement via electrically induced magnetic moments

TL;DR

This paper investigates how to enhance magnetic responses in atomic gases through electrically induced magnetic moments, analyzing mechanisms like multiphoton resonance to improve negative refraction applications.

Contribution

It provides a detailed analysis of the physical mechanisms behind magnetic response enhancement in three-level atomic systems, comparing coherent and incoherent driving methods.

Findings

Enhancement occurs at multiphoton resonance via scattering processes.

Comparison reveals the physical mechanism behind magnetic response enhancement.

Conditions for optimizing the enhancement are discussed.

Abstract

The realization of negative refraction in atomic gases requires a strong magnetic response of the atoms. Current proposals for such systems achieve an enhancement of the magnetic response by a suitable laser field configuration, but still rely on high gas densities. Thus further progress is desirable, and this requires an understanding of the precise mechanism for the enhancement. Therefore, here we study the magnetic and electric response to a probe field interacting with three-level atoms in ladder configuration. In our first model, the three transitions are driven by a control field and the electric and magnetic component of the probe field, giving rise to a closed interaction loop. In a reference model, the coherent driving is replaced by an incoherent pump field. A time-dependent analysis of the closed-loop system enables us to identify the different contributions to the medium response. A comparison with the reference system then allows one to identify the physical mechanism that leads to the enhancement. It is found that the enhancement occurs at so-called multiphoton resonance by a scattering of the coupling field and the electric probe field mode into the magnetic probe field mode. Based on these results, conditions for the enhancement are discussed.