Heralding single photons from a high-Q silicon microdisk

Integrated quantum photonics has recently attracted considerable attention due to the promise of realizing chip-scale quantum information processing with unprecedented capability and complexity. Their implementation relies essentially on a high-quality chip-scale photon source to support diverse quantum functionalities. Microresonator-based photon sources are a promising solution for generating bright, pure, and single-mode photons with excellent power efficiencies. However, their low Klyshko efficiency, typically around a few percentages, is a major bottleneck restricting this type of device from practical quantum applications. In this paper, we improve the Klyshko efficiency of a telecom-band heralded single-photon source from a high-Q silicon microdisk to as high as 48%. We characterize the photon antibunching properties at the same time, with a conditional self-correlation below 0.01 at a detected photon pair flux up to 0.002 counts per 5 ns gate at a repetition rate of 3 MHz. At an optical peak power of 73 mu W, the photon source has a large photon flux of 0.01 counts per gate, a high Klyshko efficiency of 46%, and a strong photon antibunching with a conditional self-correlation smaller than 0.05. In particular, we find a relation between the Klyshko efficiency and high-order correlations for the first time to our knowledge. This relation contributes to the understanding of photon statistics in the heralding process and also provides a method to verify the Klyshko efficiency. The improved heralding efficiency, together with the great photon antibunching property and power efficiency, renders the microresonator-based photon source promising for diverse quantum applications, including linear-optical quantum computing and quantum key distribution.