We propose a method that enables efficient storage and retrieval of a photonic excitation stored in an ensemble quantum memory consisting of Lambda-type absorbers with non-zero Stokes shift. We show that this can be used to implement a multimode quantum memory storing multiple frequency-encoded qubits in a single ensemble, and allowing their selective retrieval. The read-out scheme applies to memory setups based on both electromagnetically-induced transparency and stimulated Raman scattering, and spatially separates the output signal field from the control fields.
@article{arxiv.0710.5033,
title = {Efficient spatially-resolved multimode quantum memory},
author = {K. Surmacz and J. Nunn and F. C. Waldermann and K. C. Lee and Z. Wang and I. A. Walmsley and D. Jaksch},
journal= {arXiv preprint arXiv:0710.5033},
year = {2009}
}