Electrically Pumped Ultrabright Entangled Photons on Chip

Entangled photon sources (EPSs) are essential for quantum science and technology. Despite advancements in integrated optical platforms like thin-film lithium niobate, a scalable, high-performance, chip-scale EPS has remained elusive. We address this by demonstrating an electrically pumped, post-selection-free polarization EPS, achieved through hybrid integration of a distributed feedback laser with a thin-film lithium niobate chip, which integrates periodically poled lithium niobate waveguides, a beam splitter, and a polarization rotator combiner. By injecting current into the chip, we realize a high-performance EPS with a bandwidth of 73 nm and an entanglement pair generation rate of 4.5×10^{10} pairs/s/mW. The polarization entanglement shows Bell-state fidelities above 96% across frequency-correlated modes. This compact, integrated EPS enables key applications, including high-speed quantum key distribution via wavelength division multiplexing, satellite-based quantum communication, and entanglement-based quantum metrology.