# Comment on ''Inverse Doppler shift and control field as coherence generators for the stability in superluminal light''

## TL;DR

The paper critiques a previous study on inverse Doppler shift and superluminal light, arguing that the parameters used do not produce observable superluminal effects and that the Doppler shifts are negligible.

## Contribution

It clarifies that the parameter choices in the criticized study do not demonstrate superluminal light or significant Doppler shifts.

## Key findings

- Doppler shifts are negligible at the given parameters.
- The probe wavelength is in the decimeter band, not supporting superluminal effects.
- Simulations do not evidence superluminal light phenomena.

## Abstract

In their study of inverse Doppler shift and superluminal light [Phys. Rev. A 91, 053807 (2015)], Ghafoor et al. consider a three-level atomic arrangement with transitions in the optical domain. In fact, the values they give to the parameters lead to a probe wavelength lying in the decimeter band. We point out that the Doppler shifts are then negligible and remark that the simulations performed by Ghafoor et al. do not evidence any superluminal effect.