Due to the existence of flatbands within the band structure, twisting photonics introduces a possibility to enhance the interaction between excitons in single QDs and cavity photons because of the extremely high quality factor (Q) in theory. In this work, we report a Purcell effect between single QDs and moiré photonic crystal nanocavities. The moiré photonic crystal nanocavities in a GaAs slab with QDs embedded are formed by twisting two layer photonic crystal structures with specific angles. High Q, low mode volume and large overlap between QDs and cavity mode field have been achieved by optimizing the filling ratio of the single-layer photonic crystal, with which a Q of fundamental modes about 2000 is experimentally demonstrated. A photoluminescence intensity enhancement of a factor about 8.4 is observed when a single QD is in resonance with a cavity mode, with a Purcell factor of about 3.0 confirmed through the lifetime measurement. This result shows the potential of moiré photonics to implement solid-state cavity quantum electrodynamics for future optical quantum information processing.

Solid‐state quantum light sources based on semiconductor quantum dots (QDs) are increasingly employed in photonic quantum information applications. Especially when moving towards real‐world scenarios outside shielded lab environments, the efficient and robust coupling of nanophotonic devices to single‐mode optical fibers offers substantial advantage by enabling “plug‐and‐play” operation. In this work we present a fiber‐pigtailed cavity‐enhanced source of flying qubits emitting single indistinguishable photons at clock‐rates exceeding 1 GHz. This is achieved by employing a fully deterministic technique for fiber‐pigtailing optimized QD‐devices based on hybrid circular Bragg grating (hCBG) micro‐cavities. The fabricated fiber‐pigtailed hCBGs feature emission lifetimes of ps, corresponding to a Purcell factor of ∼9, a suppression of multi‐photon emission events with g ⁽²⁾ (0) < 1 %, a photon‐indistinguishability % and a measured single‐photon coupling efficiency of 53 % in a high numerical aperture single‐mode fiber, corresponding to 1.2 Megaclicks per second at the single‐photon detectors under 80 MHz excitation clock‐rates. Furthermore, we show that high multi‐photon suppression and indistinguishability prevail for excitation clock‐rates exceeding 1 GHz. Our results show that Purcell‐enhanced fiber‐pigtailed quantum light sources based on hCBG cavities are a prime candidate for applications of quantum information science.

Topological photonics offers the potential to develop quantum light sources with inherent robustness against structural disorders. To date, topologically protected edge or corner states have been investigated for this purpose. Here, for the first time, we exploit a topological bulk state with vertical directionality to enhance the light emission from a single semiconductor quantum dot (QD). An irregular ‘Q’-shaped cavity is applied for establishing topological robustness. We experimentally demonstrate a 1.6-fold Purcell enhancement of single-photon emission in the topological bulk cavity, with tolerance to the emission wavelength or the positioning of the coupled QD. Simulations indicate that such a QD-cavity coupling system can retain a Purcell factor exceeding 1.6 under a broad spectral detuning range of 8.6 nm or a coverage area of 2.5 μm². Furthermore, the optimized cavity structure integrated with a reflector predicts a high single-photon extraction efficiency up to 92%. Our results offer a novel approach to develop topologically protected quantum light sources with high extraction efficiency and robust QD-cavity interaction against irregular cavity boundaries.