Quantum dots are both excellent single-photon sources and hosts for single spins. This combination enables the deterministic generation of Raman-photons—bandwidth-matched to an atomic quantum-memory—and the generation of photon cluster states, a resource in quantum communication and measurement-based quantum computing. GaAs quantum dots in AlGaAs can be matched in frequency to a rubidium-based photon memory, and have potentially improved electron spin coherence compared to the widely used InGaAs quantum dots. However, their charge stability and optical linewidths are typically much worse than for their InGaAs counterparts. Here, we embed GaAs quantum dots into an n-i-p-diode specially designed for low-temperature operation. We demonstrate ultra-low noise behaviour: charge control via Coulomb blockade, close-to lifetime-limited linewidths, and no blinking. We observe high-fidelity optical electron-spin initialisation and long electron-spin lifetimes for these quantum dots. Our work establishes a materials platform for low-noise quantum photonics close to the red part of the spectrum.

量子点既是出色的单光子源，也是单次自旋的宿主。这种组合能够确定性地产生拉曼光子——带宽与原子量子存储器相匹配——以及光子簇状态的产生，这是量子通信和基于测量的量子计算中的一种资源。AlGaAs 中的 GaAs 量子点可以在频率上与基于铷的光子存储器匹配，并且与广泛使用的 InGaAs 量子点相比，具有潜在改善的电子自旋相干性。然而，它们的电荷稳定性和光学线宽通常比 InGaAs 同类产品差得多。在这里，我们将 GaAs 量子点嵌入到n - i - p- 专为低温操作而设计的二极管。我们展示了超低噪声行为：通过库仑阻塞进行电荷控制、接近寿命限制的线宽和无闪烁。我们观察到这些量子点的高保真光学电子自旋初始化和长电子自旋寿命。我们的工作为接近光谱红色部分的低噪声量子光子学建立了一个材料平台。