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

TL;DR

This paper demonstrates light storage using four-wave mixing and electromagnetically induced transparency in cold atoms, including the first experimental storage and retrieval of an image, with detailed physics analysis and potential applications.

Contribution

It introduces a novel method for storing and retrieving images via FWM and EIT in cold atoms, expanding quantum memory capabilities.

Findings

Stored and retrieved both probe and idler fields with oscillations due to magnetic fields.

First experimental demonstration of image storage using FWM.

Identified two sources of the retrieved idler field depending on detuning.

Abstract

We performed an experiment to observe the storages of an input probe field and an idler field generated through an off-axis four-wave mixing (FWM) process via a double-lambda configuration in a cold atomic ensemble. We analyzed the underlying physics in detail and found that the retrieved idler field came from two parts if there was no single-photon detuning for pump pulse: part 1 was from the collective atomic spin (the input probe field, the coupling field and the pump field combined to generate the idle field through FWM, then the idler was stored through electromagnetically induced transparency.); part 2 was from the generated new FWM process during the retrieval process (the retrieved probe field, the coupling field and the pump field combined to generate a new FWM signal). If there was single-photon detuning for pump pulse, then the retrieved idler was mainly from part 2. The retrieved two fields exhibited damped oscillations with the same oscillatory period when a homogeneous external magnetic field was applied, which was caused by the Larmor spin precession. We also experimentally realized the storage and retrieval of an image of light using FWM for the first time. In which, an image was added into the input signal. After the storage, the retrieved idler beams and input signal carried the same image. This image storage technique holds promises for application in image processing, remote sensing and quantum communication.