Controllable-dipole quantum memory

Abstract

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} $\ddot{I}„=\int dt{g}^2(t)/\hat{I}º$, where $g(t)$ is the time-dependent coupling and $\hat{I}º$ 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.

7 pages, 6 figures