Waveguide-coupled single collective excitation of atomic arrays
The group of Julien Laurat from Laboratoire Kastler Brossel has recently published interesting results where by using arrays of individual caesium atoms trapped along an optical nanofibre, they observed a single collective atomic excitation 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. They 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%. The 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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Via an external write pulse on the |g⟩→|e⟩ | g ⟩ → | e ⟩ transition, a collective entangled state with one ‘spin–flip’ excitation is created.