Storage and retrieval of ghost images in hot atomic vapor.

Ghost imaging is an imaging technique in which the image of an object is revealed only in the correlation measurement between two beams of light, whereas the individual measurements contain no imaging information. Here, we experimentally demonstrate storage and retrieval of ghost images in hot atomic rubidium vapor. Since ghost imaging requires (quantum or classical) multimode spatial correlation between two beams of light, our experiment shows that the spatially multimode correlation, a second-order correlation property of light, can indeed be preserved during the storage-retrieval process. Our work, thus, opens up new possibilities for quantum and classical two-photon imaging, all-optical image processing, and quantum communication.