Elaboration of the Ahn-Weinacht-Bucksbaum scheme for information storage or retrieval through a quantum phase with a single operation

We present a scheme for information storage or retrieval through a quantum phase with a single operation, which generalizes the Ahn-Weinacht-Bucksbaum (AWB) scheme proposed and demonstrated in a recent experiment on N-state Rydberg atoms by Ahn, Weinacht, and Bucksbaum [Science 287, 463 (2000)]. Our scheme elaborates the AWB scheme through removing its original constraint on the smallness of the product of time and atom-light interactions by exactly evaluating the involved unitary transformations, and it is proved to have several pronounced advantages over the original one.