Static Magnetic Field Swaps Slow and Fast Light in a V-Type Degenerate Media

In this letter, we propose a novel mechanism for controlling the slow and fast light propagation in a Doppler-broadened V-type degenerate atomic medium under the influence of a static magnetic field. We have demonstrated that the optical response of the medium can be switched from transparent to absorptive at the resonance frequency center by turning the magnetic field on/off. Using a static magnetic field as a tuning “knob,” we can control the magnitude and sign of the group refractive index by changing the magnitude or direction of the magnetic field, enabling the transition of a light pulse from ultraslow to ultrafast propagation. In addition, the required switching times from slow to fast light propagation are also presented. In particular, the results are applied in a room-temperature medium under the influence of the Doppler effect, which makes the model close to the realistic experiments. The research results are valid for quantum information storage and processing devices.