Waveguide-coupled single collective excitation of atomic arrays

• Published in: Nature (London) Vol. 566; no. 7744; pp. 359 - 362
• Main Authors: Corzo, Neil V., Raskop, Jérémy, Chandra, Aveek, Sheremet, Alexandra S., Gouraud, Baptiste, Laurat, Julien
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 01-02-2019; Nature Publishing Group
• Subjects: 639/624/400/1021; 639/766/483/481; Atomic excitations; Atoms; Atoms & subatomic particles; Cesium; Cold; Dielectric waveguides; Electrodynamics; Humanities and Social Sciences; Interfaces; Letter; Light; multidisciplinary; Nanofibers; Nonlinear optics; Optics; Photons; Physics research; Quantum electrodynamics; Quantum theory; Science; Science (multidisciplinary); Waveguides
• ISSN: 0028-0836; 1476-4687
• DOI: 10.1038/s41586-019-0902-3

Considerable efforts have been recently devoted to combining ultracold atoms and nanophotonic devices
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–
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to obtain not only better scalability and figures of merit than in free-space implementations, but also new paradigms for atom–photon interactions
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. Dielectric waveguides offer a promising platform for such integration because they enable tight transverse confinement of the propagating light, strong photon–atom coupling in single-pass configurations and potentially long-range atom–atom interactions mediated by the guided photons. However, the preparation of non-classical quantum states in such atom–waveguide interfaces has not yet been realized. Here, by using arrays of individual caesium atoms trapped along an optical nanofibre
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,
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, we observe a single collective atomic excitation
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coupled to a nanoscale waveguide. The stored collective entangled state can be efficiently read out with an external laser pulse, leading to on-demand emission of a single photon into the guided mode. We characterize the emitted single photon via the suppression of the two-photon component and confirm the single character of the atomic excitation, which can be retrieved with an efficiency of about 25%. Our results demonstrate a capability that is essential for the emerging field of waveguide quantum electrodynamics, with applications to quantum networking, quantum nonlinear optics and quantum many-body physics
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.
Waveguide quantum electrodynamics is used to couple a single collective excitation of an atomic array to a nanoscale waveguide; the excitation is stored and later read out, generating guided single photons on demand.