Hetet, GabrielLongdell, JevonSellars, MatthewLam, Ping KoyBuchler, Benjamin2015-12-100031-9007http://hdl.handle.net/1885/52769We investigate the properties of a recently proposed gradient echo memory (GEM) scheme for information mapping between optical and atomic systems. We show that GEM can be described by the dynamic formation of polaritons in k space. This picture highlights the flexibility and robustness with regards to the external control of the storage process. Our results also show that, as GEM is a frequency-encoding memory, it can accurately preserve the shape of signals that have large time-bandwidth products, even at moderate optical depths. At higher optical depths, we show that GEM is a high fidelity multimode quantum memory.Keywords: Control theory; Electron multipliers; Gems; Atomic systems; Bandwidth products; Dynamic formations; External controls; Gradient echoes; High fidelities; Information mappings; K spaces; Multi modals; Multimode; Optical depths; Optical-; Polaritons; Quantum200810.1103/PhysRevLett.101.2036012016-02-24