One In, One Out

Abstract

PHYSICS The successful development of optical-based quantum information processing and quantum cryptography will require the ability to store and retrieve known numbers of photons in a medium of choice. Despite significant progress in techniques to store single photons within a cloud of rubidium or cesium atoms, the overall efficiency of the storage and retrieval process in such systems has been limited by low retrieval efficiencies and relatively high noise levels. Laurat et al. show that the retrieval efficiency of single excitations stored in an ensemble of cold cesium atoms can be increased by careful optimization of the experimental parameters. The authors found that by increasing the number of photons in each read pulse to approximately 107 and increasing the optical depth of the atomic ensemble, they could raise retrieval efficiency to ∼50%, with a concurrent order-of-magnitude reduction in two-photon emission events. They argue that such an improvement bodes well for long-distance quantum communication. — ISO Opt. Express 14 , 6912 (2006).