Mid-infrared entanglement in 220 nm silicon

Silicon photonics in the mid-infrared is a promising platform for quantum technologies. Previous demonstrations of silicon mid-infrared quantum optics have used a 340 nm silicon layer height. In this work, we use industry-standard 220 nm silicon to implement a novel, to the best of our knowledge, photon-pair source with a peak coincidence-to-accidental ratio (CAR) of 20.9±2.9 at a net measured rate of 0.63±0.02 Hz and an inferred source efficiency of 2.85±0.04 MHz W^-2. Finally, we report the first integrated mid-infrared entanglement, generating a Bell state with a fidelity of <i>F</i>=94±2<i>%</i>.