Light Qubit Storage and Retrieval using Macroscopic Atomic Ensembles

Abstract

We present an experimentally feasible protocol for the complete storage and retrieval of arbitrary light states in an atomic quantum memory using the well-established Faraday interaction between light and matter. Our protocol relies on multiple passages of a single light pulse through the atomic ensemble without the impractical requirement of kilometer long delay lines between the passages. Furthermore, we introduce a time dependent interaction strength which enables storage and retrieval of states with arbitrary pulse shapes. The fidelity approaches unity exponentially without squeezed or entangled initial states, as illustrated by explicit calculations for a photonic qubit.

4 pages, 3 figures For his new version, the original paper has substantially rewritten to make it clearer including completely new introduction and conclusions and a rearrangement of the middle part. A minor mistake in the numerical results has been found and corrected, which resulted in higher values for the fidelities