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Journal of Modern Physics

Observation of Superluminal in Doppler Broadened Two-Level Atomic Systems in Magnetic Field

Shuangqiang Liu, Yundong Zhang, Hao Wu, Ping Yuan

Published Jan 1, 2010• 0 citations
Publisher

Abstract

A novel method to control the group velocity of light propagation in a two-level atomic system without additional optical field is proposed. Numerical result and experimental data shows that by changing the magnetic field intensity and vapor temperature, the group velocity of probe light can be controlled in an appropriate region.
DOI
10.4236/jmp.2010.14038

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Abstract The present study addresses light propagation in both the positive- and negative-group-index regimes in a degenerate atomic system with four energy levels. Both the static magnetic field and the Doppler shifts play essential roles. Operating in an electromagnetically induced transparency configuration, we demonstrate that probe absorption characteristics and the group velocity index can be manipulated by combined control of the static magnetic field and two coupling laser fields. By selectively engaging one or both coupling fields, the magnetic field serves as a switching mechanism, toggling the atomic medium's optical behavior between transparent and absorptive states. Consequently, both the magnitude and sign of the group index can be adjusted, transitioning from positive to negative values or the reverse, based on whether the magnetic field is applied or removed. Additionally, temperature significantly influences both the optical properties and group index characteristics of the atomic medium. Given that our proposed system operates at room temperature, it is well-suited to practical experimental conditions and offers potential for deployment in optical storage technologies and quantum information processing applications.
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