Image adder and subtractor based on light storage

We theoretically propose a scheme for realizing storage-based image adder and subtractor on account of the electromagnetically induced transparency (EIT). The image adder is implemented by directly storing two patterns in a four-level double-Λ\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\varLambda $$\end{document} system, while the image subtractor is achieved on the basis of the image adder and introducing a phase π\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\pi $$\end{document} to one signal field through the cross-phase modulation. Both analytical analysis and numerical simulation clearly show that, by manipulating the splitter rate of the beam splitters and the Rabi frequencies of the coupling fields, the weighted adder and subtractor of the two patterns can be accomplished. In addition, the influence of the atomic diffusion on the image adder and subtractor is also discussed, and the scheme can be easily extended to the adder and subtractor for multiple images. The current scheme may find important applications in the realization of EIT-based devices for all-optical classical and quantum information processing of images.