Controllable Storage Of Gaussian Light Pulse In Rubidium Atomic Gases

Electromagnetically induced transparency technology provides a new method for the realization of slow and stored optical information. In 1990, the Harris team proposed the electromagnetically induced transparency (Electromagnetically Induced Transparency, referred to as EIT)concept. In the case of EIT, the characteristics of medium shows strong dispersion and high transmission,which can slow down the group velocity of light. At the same time, the group velocity of light can be reduced to zero through dynamic control of coupling light intensity, stopping in the medium. Then we turn on adiabatically the coupling light, releasing the light signal stored in the medium. The realization of slowed light and optical storage technology based on EIT has great application prospect in the field of quantum computation and quantum communication. It is important for the development of quantum information technology. Early people carried out EIT experiments based on atomic hyperfine structure, Zeeman EIT realizing slow and stored light is relatively few. In this paper, based on EIT with Zeeman sub-levels of the F=2â†'F’=1 transition degenerate two level system of the D1 transition of the 87Rb isotope, we studied controllable storage of Gaussian light pulse in EIT medium.The main work as follows:1. A set of experimental system was designed and built using for studying controllable storage of Gaussian light pulse based on Zeeman EIT. The system mainly consists of laser system, light physical system, detection and control system.2. We realize Zeeman EIT on the experimental platform. In the experiment, when two laser beams with opposite circular polarizations (σ and σ+), called probing and coupling light respectively, couple transitions between Zeeman sub-levels of D1 line F=2â†'F’=1 in rubidium atoms, electromagnetically induced transparency (EIT) with reduced absorption and enhanced dispersion is achieved in the atomic medium.3. We observed the the phenomenon of slowed light. At reducing the group velocity of light, the frequency of the probe is fixed at the coupled photon resonance. Through the signal generator to control the amplitude of the output signal of the probe, thus Gaussian light pulse is obtained. And the effect of slowed light in atomic medium is detected by photoelectric detector. We have systematically investigated the influence of different coupling light intensity and rubidium cell temperature on the absolute delay time of the slowed pulse, as well as the width of the optical pulse on relative delay degree of the slowed pulse(the relative delay degree is defined as the ratio between the absolute delay time and the width of the optical pulse). The time delay of the probe pulse can be increased either by increasing the coupling light intensity or the cell temperature with the same width of the optical pulse, which results in more efficient slowing of the probe pulse. On the other hand, we observed larger relative time delay with narrower probe pulse under constant coupling intensity and cell temperature, which results in more significant temporal separation between the reference and probe pulses. Furthermore, we have achieved the largest possible temporal separation with optimized experimental parameters.4. By varying the shutting time of the coupling beam, we obtained different storage optical pulses. Experiments show that the waveform of the retrieved optical pulse is consistent with the part of pulse stored in the medium, and retrieved pulse carry the waveform information of the original light pulse.