Short-Wave Infrared Correlated Photons from Silicon Waveguides

Quantum technologies that harness the properties of superposition and entanglement promise to revolutionise many fields, from information processing to metrology. Silicon-integrated quantum photonics operating in the telecom band suffers from deleterious two-photon absorption (TPA) [1,2]. Cross-TPA reduces the brightness and ultimately the heralding efficiency [3] of spontaneous four-wave mixing (SFWM) photon-pair sources, where single photons necessarily co-propagate with a bright pump. Nonlinear losses can be mitigated by pumping and generating photons with energies close to and beyond silicon's two-photon band edge [4,5]. We report the first quantum-correlated photon pairs in the 2.1 μm short-wave infrared (SWIR) band, produced on-chip from a silicon waveguide spiral.