QUROPE Quantum Information Processing and Communication in Europe

Storing information encoded in light is critical for realizing optical buffers for all-optical signal processing1, 2 and quantum memories for quantum information processing3, 4. These proposals require efficient interaction between atoms and a well-defined optical mode. Photonic crystal fibres can enhance light–matter interactions and have engendered a broad range of nonlinear effects5; however, the storage of light has proven elusive. Here, we report the first demonstration of an optical memory in a hollow-core photonic crystal fibre. We store gigahertz-bandwidth light in the hyperfine coherence of caesium atoms at room temperature using a far-detuned Raman interaction. We demonstrate a signal-to-noise ratio of 2.6:1 at the single-photon level and a memory efficiency of 27 ± 1%. Our results demonstrate the potential of a room-temperature fibre-integrated optical memory for implementing local nodes of quantum information networks.