Cryogenic Parametric Down-Conversion in Titanium In-Diffused Lithium Niobate Waveguides

Integrated quantum photonic devices require the combination of quantum light sources, elements for guiding and manipulating the photonic states and detectors [1] . In a fully-integrated platform, the operating conditions for each component must be mutually compatible. Whilst parametric down-conversion (PDC) as a source for photonic states is well-established under ambient conditions [2] , other quantum photonic technologies require cryogenic operation temperatures, in particular superconducting single-photon detectors [3] .