Open system effects on slow light and electromagnetically induced transparency

TL;DR

This paper investigates how open system effects like decoherence influence slow light and electromagnetically induced transparency in a three-level system, providing analytic solutions and visual insights.

Contribution

It introduces a coherence vector formalism for analyzing open system effects on EIT and derives analytic expressions for the system's optical response.

Findings

Open system channels can modify the transparency and slow light effects.

Different types of decoherence can lead to gain in the system.

A geometric visualization aids understanding of the coherence dynamics.

Abstract

The coherence properties of a three-level $\Lambda$-system influenced by a Markovian environment are analyzed. A coherence vector formalism is used and a vector form of the Lindblad equation is derived. Together with decay channels from the upper state, open system channels acting on the subspace of the two lower states are investigated, i.e., depolarization, dephasing, and amplitude damping channels. We derive an analytic expression for the coherence vector and the concomitant optical susceptibility, and analyze how the different channels influence the optical response. This response depends non-trivially on the type of open system interaction present, and even gain can be obtained. We also present a geometrical visualization of the coherence vector as an aid to understand the system response.