On-chip single-photon sources are key components for integrated photonic quantum technologies. Semiconductor quantum dots can exhibit near-ideal single-photon emission, but this can be significantly degraded in on-chip geometries owing to nearby etched surfaces. A long-proposed solution to improve the indistinguishablility is to use the Purcell effect to reduce the radiative lifetime. However, until now only modest Purcell enhancements have been observed. Here we use pulsed resonant excitation to eliminate slow relaxation paths, revealing a highly Purcell-shortened radiative lifetime (22.7 ps) in a waveguide-coupled quantum dot–photonic crystal cavity system. This leads to near-lifetime-limited single-photon emission that retains high indistinguishablility (93.9%) on a timescale in which 20 photons may be emitted. Nearly background-free pulsed resonance fluorescence is achieved under π-pulse excitation, enabling demonstration of an on-chip, on-demand single-photon source with very high potential repetition rates.

片上单光子源是集成光子量子技术的关键组件。半导体量子点可以表现出近乎理想的单光子发射，但是由于附近的蚀刻表面，这种现象在芯片上的几何形状中可能会大大降低。长期以来提出的提高不可分辨性的解决方案是使用赛尔效应（Purcell effect）来缩短辐射寿命。但是，到目前为止，仅观察到适度的赛尔增强。在这里，我们使用脉冲共振激励消除了缓慢的弛豫路径，从而揭示了在波导管耦合的量子点-光子晶体腔系统中，赛尔辐射极大地缩短了辐射寿命（22.7 ps）。这导致接近寿命的单光子发射，在可以发射20个光子的时间尺度上，保留了高不可分辨性（93.9％）。π脉冲激励，可以演示具有很高潜在重复率的片上按需单光子源。