Control of light speed: From slow light to superluminal light

TL;DR

This paper presents a scheme using far detuning Raman effect in atomic systems to control light speed, enabling transitions from slow to superluminal light by manipulating dispersion properties.

Contribution

It introduces a novel method to switch light speed from slow to superluminal using far detuning Raman effect and optical pumping in a $b1$-type atomic system.

Findings

Achieves control of light speed from subluminal to superluminal.

Demonstrates the role of optical pumping in altering dispersion.

Provides a theoretical framework for light speed manipulation.

Abstract

A scheme for controlling light speed from slower-than-c to faster-than-c in an atomic system is presented in this paper. The scheme is based on far detuning Raman effect. Two far detuning coupling fields with small frequency difference will produce two absorptive peaks for the probe field in a $\Lambda$ structure, and an optical pump between the two ground states can change the absorptive peaks into enhanced peaks, which makes the normal dispersion between the two peaks change into anomalous dispersion, so the probe field can change from slow light to superluminal propagation.