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Semiconductor quantum dots (QDs) provide useful means to couple light and matter in applications such as light-harvesting and all-solid-state quantum information processing. This coupling can be increased by placing QDs in nanostructured optical environments such as photonic crystals or metallic nanostructures that enable strong confinement of light and thereby enhance the light-matter interaction. It has thus far been assumed that QDs can be described in the same way as atomic photon emitters-as point sources with wavefunctions whose spatial extent can be disregarded. Here we demonstrate that this description breaks down for QDs near plasmonic nanostructures. We observe an eightfold enhancement of the plasmon excitation rate, depending on QD orientation as a result of their mesoscopic character. Moreover, we show that the interaction can be enhanced or suppressed, determined by the geometry of the plasmonic nanostructure, consistent with a newly developed theory that takes mesoscopic effects into account. This behaviour has no equivalence in atomic systems and offers new opportunities to exploit the unique mesoscopic characteristics of QDs in the development of nanophotonic devices that use the increased light-matter interaction. [ABSTRACT FROM AUTHOR]

This report considers how recent experimental progress on deterministic solid‐state spin–photon interfaces enables the construction of a number of key elements of quantum networks. After reviewing some of the recent experimental achievements, a discussion of their integration into Bell state analyzers, quantum non‐demolition detection, and photonic cluster state generation is presented. Finally, it is outlined how these elements can be used for long‐distance entanglement generation and quantum key distribution in a quantum network. [ABSTRACT FROM AUTHOR]

Deterministic sources of multiphoton entanglement are highly attractive for quantum information processing but are challenging to realize experimentally. In this Letter, we demonstrate a route toward a scaleable source of time-bin encoded Greenberger-Horne-Zeilinger and linear cluster states from a solid-state quantum dot embedded in a nanophotonic crystal waveguide. By utilizing a self-stabilizing double-pass interferometer, we measure a spin-photon Bell state with (67.8±0.4)% fidelity and devise steps for significant further improvements. By employing strict resonant excitation, we demonstrate a photon indistinguishability of (95.7±0.8)%, which is conducive to fusion of multiple cluster states for scaling up the technology and producing more general graph states.