Light storage based on four-wave mixing and electromagnetically induced transparency in cold atoms

摘要

We performed an experiment to observe the storage of an input probe field and an idler field generated throughnan off-axis four-wave mixing (FWM) process via a double-u0002 configuration in a cold atomic ensemble. Wenanalyzed the underlying physics in detail and found that the retrieved idler field came from two parts if there wasnno single-photon detuning for the pump pulse: Part 1 was from the collective atomic spin (the input probe field,nthe coupling field, and the pump field combined to generate the idler field through FWM; then the idler was storednthrough electromagnetically induced transparency). Part 2 was from the generated new FWM process during thenretrieval process (the retrieved probe field, the coupling field, and the pump field combined to generate a newnFWMsignal). If therewas single-photon detuning for the pump pulse, then the retrieved idlerwasmainly from partn2. The retrieved two fields exhibited damped oscillations with the same oscillatory period when a homogeneousnexternal magnetic field was applied, which was caused by the Larmor spin precession. We also experimentallynrealized the storage and retrieval of an image of light using FWM, in which an image was added into the inputnsignal. After the storage, the retrieved idler beams and input signal carried the same image. This image storagentechnique holds promise for applications in image processing, remote sensing, and quantum communication.