We present a quantum memory protocol for photons that is based on the direct control of the transition dipole moment. We focus on the case where the light-matter interaction is enhanced by a cavity. We show that the optimal write process (maximizing the storage efficiency) is related to the optimal read process by a reversal of the {\it effective time} τ=∫dtg2(t)/κ, where g(t) is the time-dependent coupling and κ is the cavity decay rate. We discuss the implementation of the protocol in a rare-earth ion doped crystal, where an optical transition can be turned on and off by switching a magnetic field.
@article{arxiv.1106.3513,
title = {Controllable-dipole quantum memory},
author = {Khabat Heshami and Adam Green and Yang Han and Arnaud Rispe and Erhan Saglamyurek and Neil Sinclair and Wolfgang Tittel and Christoph Simon},
journal= {arXiv preprint arXiv:1106.3513},
year = {2015}
}