Three-photon coherence in a ladder-type atomic system

TL;DR

This paper provides a theoretical analysis of three-photon electromagnetically induced absorption in a ladder-type atomic system, revealing the underlying four-level scheme and comparing different polarization configurations.

Contribution

It introduces a detailed theoretical model for three-photon EIA in ladder-type systems and compares polarization schemes, highlighting the equivalence of absorption coefficients with different transition strengths.

Findings

Absorption coefficients are identical across schemes except for transition strengths.

The primitive scheme is a simple four-level system.

Theoretical framework for three-photon EIA in ladder systems.

Abstract

We present a theoretical study of three-photon electromagnetically induced absorption for a ladder-type three-level atomic system. A probe beam was tuned to the lower line and two counter-propagating, linearly polarized coupling beams were tuned to the upper line. The system can be modeled with a three- (or five-) level scheme when the polarization directions of the coupling beams are parallel (or perpendicular). By calculating the absorption coefficients analytically for the two schemes, we found that the corresponding absorption coefficients were identical except for different transition strengths, and that the primitive scheme embedded in those schemes was a simple four-level scheme.