title: High-capacity spatial multimode quantum memories based on atomic ensembles.
abstract: We study spatial multimode quantum memories based on light storage in extended ensembles of Λ-type atoms. We show that such quantum light-matter interfaces allow for highly efficient storage of many spatial modes. In particular, forward operating memories possess excellent scaling with the important physical parameters: quadratic scaling with the Fresnel number and even cubic with the optical depth of the atomic ensemble. Thus, the simultaneous use of both the longitudinal and transverse shape of the stored spin wave modes constitutes a valuable and so far overlooked resource for multimode quantum memories.
authors.affiliation: QUANTOP, Danish National Research Foundation Center for Quantum Optics, Niels Bohr Institute, University of Copenhagen, DK-2100 Copenhagen Ø, Denmark. anna.grodecka-grad@nbi.dk
authors.forename: Anna
authors.initials: A
authors.lastname: Grodecka-Grad
authors.forename: Emil
authors.initials: E
authors.lastname: Zeuthen
authors.forename: Anders S
authors.initials: AS
authors.lastname: Sørensen