Superluminal light propagation via quantum interference in decay channels

TL;DR

This paper investigates how quantum interference in decay channels can enable superluminal light propagation in a coherently driven atomic system, revealing potential for lossless anomalous dispersion and high refractive index with minimal absorption.

Contribution

It introduces a novel mechanism where decay-induced quantum interference enables switchable superluminal light propagation in a Y-type atomic system.

Findings

Quantum interference causes lossless anomalous dispersion.

Probe pulse can be switched from subluminal to superluminal.

System exhibits high refractive index with negligible absorption.

Abstract

We examine the propagation of a weak probe light through a coherently driven $Y$-type system. Under the condition that the excited atomic levels decay via same vacuum modes, the effects of quantum interference in decay channels are considered. It is found that the interference in decay channels results in a lossless anomalous dispersion between two gain peaks. We demonstrate that the probe pulse propagation can in principle be switched from subluminal to superluminal due to the decay-induced interference. We also show that the system exhibits a high index of refraction with negligible absorption for the driving fields. A dressed-state picture of the atom-light interaction is described to explain the numerical results.