Broadband single-photon-level memory in a hollow-core photonic crystal fibre

• Published in: Nature photonics Vol. 8; no. 4; pp. 287 - 291
• Main Authors: Sprague, M. R., Michelberger, P. S., Champion, T. F. M., England, D. G., Nunn, J., Jin, X.-M., Kolthammer, W. S., Abdolvand, A., Russell, P. St. J., Walmsley, I. A.
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 01.04.2014; Nature Publishing Group
• Subjects: 639/624/1075/397; 639/624/400/1102; 639/624/400/482; 639/766/483/481; Applied and Technical Physics; Broadband; Fibre; letter; Networks; Optical memory (data storage); Photonic crystals; Photonics; Physics; Proposals; Quantum Physics; Stores
• ISSN: 1749-4885; 1749-4893
• DOI: 10.1038/nphoton.2014.45

Storing information encoded in light is critical for realizing optical buffers for all-optical signal processing 1 , 2 and quantum memories for quantum information processing 3 , 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 effects 5 ; 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. An optical memory is demonstrated in a kagome photonic crystal fibre whose 26-μm-diameter hollow core is loaded with cesium atoms. Gigahertz-bandwidth light is stored using a far-detuned Raman interaction. It has a memory efficiency is 27 ± 1% and a signal-to-noise ratio of 2.6:1 — the highest at the single-photon level of any memory at room temperature.