We suggest an all-optical scheme for the storage, retrieval and processing of a single-photon wave packet through its off-resonant Raman interaction with a series of coherent control beams. These control beams, each with distinct carrier frequency, are distributed along the way of single-photon propagation, thus effectively forming a gradient absorption structure which can be controlled in various ways to achieve different single-photon processing functionalities. Such a controllable frequency comb is a hybrid of Raman, gradient echo memory (GEM) and atomic frequency comb (AFC) methods, therefore demonstrates many of their advantages all together in one.
@article{arxiv.1602.02322,
title = {Quantum storage based on controllable frequency comb},
author = {Xiwen Zhang and Alexey Kalachev and Philip Hemmer and Olga Kocharovskaya},
journal= {arXiv preprint arXiv:1602.02322},
year = {2016}
}